rodynaspirt.files.wordpress.com€¦ · Web viewThe motion:-it is the change of object's location as time passes according to the location of another object. Speed . is a physical

Revision 3rd prep 1st term

The motion:-it is the change of object's location as time passes according to the location of another object.

Speed is a physical quantity which is used to describe and measure the motion of object,

The two factors necessary for the description of motion1- The distance that covered by the motion 2- The time taken by the moving body to cover this distance

Speed: it is the distance moved through a unit time

What the meant by 1-A train covers a distance 240 km in two hours This means that the train moves with speed equals 120 km/h

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The measuring unit of Speed =m/s =

Revision 3rd prep 1st term 3- The speed of a car equals zeroThis means that the car is at rest

Cars and planes are usually provided with a group of counters as speedometer, mileage, hour timer and compass.

The speedometer helps us in identifying the speed of the car directly

Kinds of speed

Regular speed

The car covered equal distances in equal periods of time Or it the change of object's position by equal distances at equal period of time.

Δd is the distance moved during a period of time Δt

2- Irregular (non-uniform) speed The change of object's position by unequal distances at equal periods of time.Or the change of object's position by equal distances at unequal periods of time

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ΔdV= ــــــــــــــ Δt


Average speed

Average speed It the total distance covered by moving object divided by the total time taken to cover this distance

Relative speed

If there is a person in a car that moves at 80 kilometers in a certain direction. Then, a car moves at 90 kilometers passed him in the same direction. This means that if there is a person standing on the side of the road and he observes the speed of the moving cars (this person is called the observer).

Relative speed It is the speed of moving object relative to an observer

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dV= ــــــــــــــ t

Revision 3rd prep 1st term Graphics can possibly represent the relation between speed and time in a moving car.

- If the car starts moving from rest (speed = zero) and after one minute its speed becomes 30 km/hour.

- After another minute, its speed increases to 60 Km/hour.

- Then, the motorist had to use the brakes to slow down the car’s speed to 20 km/hour

- in the third minute and he stops completely after another minute.

* It is possible to represent the movement graphically

1-Regular speed

Trials Distance (d) Time (t) Speed (v) =d/t1 o.4 5 0.082 0.6 7.5 0.083 0.8 10 0.084 1.0 12.5 o.08

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Revision 3rd prep 1st term Relation between distanceAnd time

ObservationAll points lie on a straight line passing the intersection point of two axes.

Conclusion The distance (d) is directly proportional to the time (t)The ratio ( d/t ) is constant value which represents the regular speed The distance-time) graph for an object moves with uniform speed is straight line passing through the origin point

Relation between speed (V) and time (t)

ObservationAll points lie on a straight line parallelTo the time (X) axis

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Revision 3rd prep 1st term Conclusion

The speed remains constant as time passes The (speed-time)graph for an object moves with regular

(uniform) speed is a is straight line parallel to the time axis

Facts about regular speed.1- The (distance-time) graph for regular motion at constant speed is represented by a straight line passing through the origin point

2- The (speed –time) graph for regular motion at constant speed is represented by a straight line parallel to the time axis

2-Irregular speed

What is the concept of acceleration?!☼ When the car’s speed increases at a constant rate (in a specific direction) and this case the movement is described as “accelerating motion".( Positive acceleration)

☼ But, if the car’s speed decreases each second until it stops, the movement is described as a deceasing acceleration (negative acceleration).

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Accelerationis the result of dividing the change in the car’s speed ∆ V and the time ∆ t in which the change occur

This means that:

Acceleration It is the value of change of an object’s speed in one second

Acceleration units = meters/second 2 = m/s2

Acceleration increases if the object’s speed increases by time.Its final speed is greater than its initial speed

Acceleration decreases if the object’s speed decreases by time.

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Final speed (V2) – initial speed (V1) Acceleration (a) = Time (∆t)

Acceleration (a) = change in speed (∆ V) / time (∆ t)

Revision 3rd prep 1st term Its initial speed is greater than its final speed

Uniform acceleration An object starts its movement from rest and in a straight line Its speed record each 5 seconds

Time (t) second 0 5 10 15 20 25 30Speed (V) meters/second 0 10 20 30 40 50 60

Observation The object’s speed increase during movementThe object’s speed increase by 10 m/s every 5 seconds

The object’s acceleration in the 1st 5 sec= = = 2m/sec2

The object’s acceleration in the 2nd 5 sec= = = 2m/sec2

That means acceleration remains constant

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V2 –V1

tt

t

20- 105

t

t

V2 –V1

tt

t

10- 05

t

t

Speed (V)m/s

Time (t) sec


1 – Scalar physical quantities It is the physical quantity that has magnitude only and has no direction.

Scalar physical quantities Its measuring unite Mass Kilogram (kg)Length Meter (m)Speed m/s or km/h Time Second or hour Energy Joule Temperature ºC or F

2 – Vector physical quantities It is the physical quantity that has magnitude and direction.

Vector physical quantities Its measuring uniteAcceleration m/s2

Force Newton

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1 -Scalars 2 - Vectors

Revision 3rd prep 1st term Velocity m/sDisplacement Meter Weight Newton

Distance It is the actual length of the path that of a moving object takes from the start point to the end point.

DisplacmentIt is the length of the shortest straight line between two positions ((primary and final position))

Comparison between distance and displacement.Points of comparison Distance DisplacementDetermined by Magnitude only Magnitude and

directionIts kind Scalar quantity Vector quantity

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Distance and displacement

Revision 3rd prep 1st term Measuring unite Meter or kilo meter Meter or kilo meter.

it is the rate of change of displacement.Or It is the displacement covered in one second (unite time)

Average velocity = displacement / total time

♣Distance = 30 + 60 + 30 = 120 meter♣Displacement = 60 meter in eastward direction.☼ the average speed = 120/60 = 2 m/s ☼the average velocity= 60/60= 1 m/s

Comparison between the speed and the velocityPoints Speed Velocity

Definition It is the distance covered in a unit time

It is the displacement covered in a unite time.

Determine by Magnitude only. Magnitude and direction.

Its kind Scalar Vector

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Velocity

Revision 3rd prep 1st term Measuring unite m/s or km/h M/s or km/h

Technological application

Plane A takes a longer time than plane B , because it flies in the opposite direction of wind.

So, the wind resistance is greater and it needs larger amount of fuel than the plan B to cover the same distance.

If you look at the shinning smooth surface (like the mirror) you can see an image of your face.

All this happens as a result of the rejection of light (its bouncing off) on the water surface or the mirror surface.

Light ReflectionIt is the phenomenon of the light bouncing off in the same medium when it meets a reflecting surface

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The properties of the image of the objects formed by the plane mirror

1- upright2- equal to the object.3- laterally inverted.4- virtual image (cannot be received on a screen) 5- The distance of the object to the mirror = the distance of its image to the mirror. 6-The straight line connecting the object and its image is perpendicular on the surface of the mirror

The word Ambulance is written in a converted way on the Ambulance car?

To appear in the mirror of the cars in front of Ambulance written in correct way and can be read by the drivers

Activity >>> to discover the two laws of light reflection

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The Plane mirrors


The ResultsLaws of the reflection of light:1 -First law : angle of incident = angle of reflection.

2 -Second law : the incident light ray and the reflected light, Ray and the normal all lie in one plane perpendicular to the reflecting surface

Concepts concerning reflection of light:

When a ray of light strikes a reflecting surface, it is reflected in the same medium.

The incident ray: it is the light ray thatfalls on the reflecting surface. The reflected ray: it is the light ray that bounces from the reflecting surface

Angle of incidence: it is the angle between the incident ray and the normal.

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Angle of reflection: it is the angle between the reflected light ray and the normal.

The incident ray which falls perpendicular on a reflecting surface reflect on itself?

Because the angle of incident and the angle of reflecting = zero

It is a mirror that its reflecting surface is a part of a hollow sphere, and there are two types of the spherical mirrors. spherical mirrors.

The types of the spherical mirrorsConcave mirror Convex mirror

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The spherical mirrors

Revision 3rd prep 1st term Shining surface is a part of the inner surface of the sphere.

Shining surface is a part of the outer surface of the sphere.

It converge (collect) rays. It diverges light rays.

The stainless –steel spoon is considered as a spherical mirror? Because its inner surface is concave mirror while the its outer

surface is convex mirror

Concepts related to the spherical mirrors Concep

tDefinition Figure

1-Centre of mirror curvature (C):

Is the Centre of the sphere that the mirror is considered a part of.The position of the center of curvature of the concave mirror (in front of the reflecting surface In the convex mirror behind the reflecting surface).

2-The radius of curvature of the mirror (r):

Is radius of the sphere that the mirror is a part of the radius of curvature of the mirror (r).

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Revision 3rd prep 1st term 3-The pole of the mirror (p):

Is the point that is in the middle of the reflective surface of the mirror

4-The principal axis (cp)

Is the straight line that passes by the pole of the mirror and its center of curvature

5-The secondary axis

Any straight line that passes by the center of curvature of the mirror and any point on its surface besides the pole of the mirror

6-The focus of the concave mirror

it is the point collection of the reflected light rays (in the concave mirror)real in case of the concave mirrorvirtual in case of the convex mirror

7- focal length of the mirror (f)

It is the distance between the focus of mirror(f) and its pole(P)

Each spherical mirror has uncountable number of secondary axes and only principal axes

How to determine concave mirror focal length?

The materials:A concave mirror - screen.

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Revision 3rd prep 1st term The steps:

1-Place a concave mirror facing the sun ray

2-Move the screen in front of the reflecting surface to obtain the smallest and clearest image (lit point)

3 -Measure the distance between the lit point and the pole of the mirror, this distance is the focal length (f) of the concave mirror.

Conclusion: 1-The rays collect in one point that can be received on a screen

2-The point of the collection of the parallel rays called The focus of the concave mirror

3-The distance between the focus of the concave mirror and its pole is called focal length of the mirror

The focus of the concave mirror the point of the collection of the parallel rays after being reflected from the concave mirror

focal length of the mirror The distance between the focus of the concave mirror and its pole

☼ Focal length = 1/2 radius of curvature f = 1/2 R☼

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Comparison between Real and Virtual image.Real image Virtual image

It is the image that can be received on screen

It is the image that cannot be received on screen

It formed as result of the intersection of reflected light rays

It formed as result of the intersection of extensions light rays

It is always inverted It is always upright

The image formed by the concave mirror

path of the incident ray

path of the reflected ray

Explanation Figure

The incident light ray parallel to the principal axis of the mirror.

It reflects passing through the focus F

The incident light ray passing through the focus F

It reflects parallel tothe principal axis

The incident light ray passing through the Centre of curvature C

It reflects back on itself

Properties of the mirror image

Objects postions Image properties The image positions.

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Revision 3rd prep 1st term Between the focus and the centre of curvature

- Real – inverted – small in the object

At the centre of curvature of the mirror.

- Real- inverted. - Same size as object

At a distance greater than the radius of curvature.

- Real - inverted - larger than object

Behind the mirror

- Virtual - Upright- magnified

The images of the object in front of a convex mirror is always

- smaller than the object,

- upright - virtual (not

received on a screen)

Concave mirror is used in solar ovens and solar furnaces? To collect a large amount of solar energy in the focus of mirror for cocking food or melting metals

Activity >>> Determine half the radius of the concave mirror.

The materials:

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Revision 3rd prep 1st term A concave mirror – a holder for the mirror – light box with a hole

The steps

1-Place the mirror on a holder in front of the light source (lit hole).2-Move the mirror nearer and farther until an image of the hole is formed next to it and is equal to it.

3-Measure the distance between the mirror and the hole, it is equal to the radius of curvature of the mirror.

Deduce: The focal length of the mirror (f) = R/2

The uses of convex mirror1-on the passing side of car to form an erect and smaller image for the way behind the car2- It used in the turning off the road and parking3- it is suitable for shops and supermarkets—used as anti-thief!!

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LensIt is a transparent medium that refracts the light and is limited with two spherical surfaces

and is usually made of glass or plastic

Uses of lenses: 1 – in medical eye glasses ((for reading or walking))2 – in fixing watches. 3 – In war they use binoculars to follow the battle.4 – used in manufacture of many things like Projector, cameras and magnifying lenses.

The types of lenses:1 Convex lens (converging) Concave lens (diverging)

Its structure

It is thick at the centre and less thickness at the tips.

It is thin at its centre and thicker at the tips.

Its function Collect the light rays falling on it so it is called converging lens

diverge the light rays falling on it so it is called diverging lens

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pictures

Study the previous figure and identify the following concepts: Concept Definition Figure

1-The centre of curvature of the lens face (c):

Is the centre of the sphere where this face is a part of it .

2-The optical centre of the lens (p)

Is a point inside the lens placed on the principal axis in the mid distance between its faces .

3 -The radiusof curvature of the face of the lens (p):

Is half the radius of the sphere where the face is a part of

4-The principal axis Is the line between the optical centre of the lens passing by the optical centre of the lens

The secondary axis It is any line passes by the optical center of the lens except the principal axis.

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Revision 3rd prep 1st term The focus of the lens (F) (principal focus)

It is the point of collection of the refracted light rays - it is produced

when a beam of parallel rays falls parallel t the principal axis of a lens.

- It is real in case of the convex lens. And virtual in case of concave lens.

The focal length of the lens (f)

It is the distance between the focus and optical center of the lens.

F = 1/2 r

Note Each lens has only one principal axis and more than one secondary axes.

The lens has two centers of curvature?Or … the lens has two foci. ?

because it has two circular surfaces.

A: The convex lens The focus of the convex lens (converging):If the sun ray or any light from any distant source fall on the lens we notice that ray passing through the lens is collected in one point called “the focus of the lens”.

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Activity >>>Determine the focal length of the convex lens

Materials: A convex lens - screen - lens holder - Distance source of light (can use the sun ray)

Conclusion 1 – Convex lens is a converging les collect refracted rays. 2 – the point of collection rays is called " the focus of the lens (F)" 3 – the distance between the focus of he lens and its optical center is called " focal length (f) 4 – (f) = 1/2 ( r ) radius of curvature.

The image formed by the convex lens can be received on the screen? Because it is a real image

A piece of paper can be burned by a convex lens? Because convex lens can converge and direct sunlight in a point which is burned.

**The path of rays falling on the concave lenses

When ray incident parallel to principal axis, it refract passing through focus.

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When ray incident pass through focus, it refract passing parallel to principal axis.

When ray incident pass through optical center it pass without refraction.

** the position of the images formed and their properties can be determined by using only two rays of the previous three rays.

The cases of the formation of the images by the convex lens (collective):To determine the position and characteristics of the formed image by the convex lens, follow the following steps:

1-Use the protractor and draw the convex lens

2-Draw the principal axis of the lens (it is a straight line passing by the focus and the optical centre of the lens).

3-Determine on it the position of the focus (f) and twice the focal length (c) on the principal axis from both sides of the lens.

4-Draw a ray coming from the highest point of the object so it falls parallel to the principal axis thus refracts and leaves the lens and passes through the focus

5-Draw a ray from the same point passing by the visual centre of the lens thus leaves with no refraction.

6-To determine the position when two respected of the two penetrating rays determines the image of the lit point.

7-Determine the position and characteristics of the images formed in the six cases shown in the following table and compare the results you obtain to those present in the table.

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The Properties of the image formed by the lensesA: convex lens

Science, technology and Society

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Revision 3rd prep 1st term The opposite figure shows how to make an activity to identify properties of the image formed by a convex lens by changing the focal length.

B: Concave lensWe can replace convex lens by a concave one in the last activity, the formed image can not be received on the screen, because the incoming rays diverge after refraction:

The properties of the formed image by the concave lens:

The concave lens is known as the diverging lens? Because it diverges the rays after they pass through it.

The image formed by the concave lens is a virtual image? Because it can not be received on a screen.

Applications on lenses: Lenses are used in many things as :

1 – optical devices as

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Revision 3rd prep 1st term - Telescopes : use to enlarge images for the heavenly bodies.- Microscope : use to magnify images of tiny bodies.

2 – use in making medical glasses to treat the vision defects.

The eye works in such way: - the light rays reflect from the body to

fall on the eye. - The light rays refract when passing

through the cornea then the lens (convex lens).

- The refracted rays are collected on the retina forming a small, real inverted image.

Note The optic nerve transmits the image to the brain which re-corrects the image to become erect and in its natural size.

the diameter of the eye ball is distance between the optical center of the lens and the retina.

To see clearly, the image must be formed on the retina. The normal person can see clearly near objects at distance not less

than 25cm, and for objects at a distance up to 6 meter.

The use of lenses to treat the vision defects

Short-sightedness:It is a vision defect through which near objects can be seen clearly but far objects seem distorted.

Long-sightedness:

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The vision

Revision 3rd prep 1st term It is a vision defect through which far objects only can be seen clearly but close objects are not seen clearly.

Vision defects occur? Because the eye cornea is not always convex or the eye is not always spherical.

The convex lens is used to correct the long-sightedness?? To collect the rays coming from the near object, so the image is formed on the retina.

The use of lenses to treat the vision defects 1 Short-sightedness Long – sightedness

The images of near objects

Can be seen clearly Cannot be seen clearly

The images of far objects

Cannot be seen clearly Can be seen clearly

The position of the images concerning the retina

In front of the retina Behind the retina

4- causes The diameter of the eyeball is too largeOr The lens is too convex

The diameter of the eyeball is too shortOr The lens is thin

The correction By using a concave lens By using a convex lens

short- Long sightedness

Correcting short- Long sightedness

Contact lenses: The contact lenses are used instead of the glasses. It is very thin lenses made of plastic, and can stick to the eye cornea by the eye fluid

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Science, Technology, and SocietyCataract ( Science integration )Cataract is one of the most dangerous diseases that injure the eye as a result of:- old age,- illness, - side effects of drugs - genetic readiness.

The result of Cataract: The difficulty of vision as a result of the darkness of the eye lens.

Treatment of cataract: Exchange the eye lens with plastic lens transplanted permanently in the eye by surgery.

Land measurement:Land surveyors and topographical scientists use a mirror provided with later ray to determine heights and distances and to make very accurate measurements to calculate the time that a light beam bounced from a distant point and returns to its source.

Universe It is the space which contains all the galaxies, stars, planets, moons and living organisms and everything.

The universe is vast beyond comprehension.

The sun and the earth are a tiny part in the universe.

In the universe groups of stars are gathered to form galaxies . The universe contains many galaxies and each galaxy has a distinctive shape according to the harmony and order of the groups of stars in it. The sun is one of the stars of our galaxy (Milky Way).

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Revision 3rd prep 1st term The galaxy

They are groups of stars that rotate together in cosmic space by the effect of gravity

Galaxies ClustersThey are groups of galaxies in the space.

The Milky Way the old (large) stars gather in the center.The recent small stars are located in spiral arms of the galaxy. The sun is a star of millions of stars that rotate around the center of Milky Way galaxy.

The Milky Way is given that name?Because it appears in the sky at night as a splashing milk or spreading straw.

The Milky Way galaxy contains all the stars we see at night in the sky.

The solar systemIt is the sun and eight planets revolving around it.

- Planets revolve around the sun and the sun and the surrounding planets revolve around the centre of the galaxy (Milky Way).

- The sun takes about 220 million years to complete one rotation around the centre of the galaxy.

- The solar system is located in one of the spiral arms of the Milky Way on the edge of the galaxy.

- The earth is one of the planets that rotate around the sun.

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The EarthIt is the planet of life

The universe: It is a wide and extended space that contains galaxies. The number of galaxies in the universe is about 100,000 million galaxies

Galaxies: Galaxies gather in clusters including the Milky Way which contains the sun.

The Milky Way It contains the sun and the solar system.The solar system: It is the sun and eight planets revolving around itThe earth The planet of life

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Revision 3rd prep 1st term Measuring the distances through the universe:

The distance between stars are very large, so it measured by unite called "light year"

A light-year The distances in the universe are so vast so that they are measured by the light-years.

The light-year is the distance that light travels in a year.- Since the speed of light equals 300000 km per second,- this distance is 946000 million km, ((9.467 × 1012 ))

The distance between the sun and a star is 3 light years, what does it mean?This means that the distance the sun and this star=3×9.467×1012

= 28.401×1012 km

Expansion of the universe

Observation Represented by raisins spacing of planets in the universe

Conclusion of the existence of spaces between the grains of raisin great void in the universe (expansion size of the universe)

Expansion of universe: It is the continuous separation between galaxies.

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Revision 3rd prep 1st term The continuous separation between galaxies? Due to the continuous motion of galaxies in the universe.

Cosmogony in ancient times: 1 -The general feature of perceptions about the universe in ancient civilizations is their relationship with the world of multiple gods and their deep belief that there is a fundamental difference between the Earth and heaven. This did not allow them to develop theories about the universe and cosmogony.

2 -The first human perception of cosmogony was in the Stone Age hundreds of thousands of years ago where myth dominated the human imagination.

3 -The human mind was developed of the ancient Egyptians and Babylonians. It became clear to them the relationship between the eternal universe and the multiple gods controlling it.

4 -astrology prevailed at both the Indian and Chinese civilization.

5 -Philosophers of the Greeks and Romans attempted to develop theories of cosmic phenomenon.

How did the universe originated ? - Many scientists believe that the universe emerged from a massive explosion called the Big Bang 15000 million years ago which resulted in all forms of matter, energy, space and time.

- There was no one to relate what happened. But the outstanding discoveries in physics and astronomy enabled scientists to trace the history of the universe from the first second fraction of its evolution.

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- They believe that the universe matter was a gaseous ball of high pressure and high temperature in a small volume. It is in a constant expansion.

- The Big Bang theory had been developed since 1933.

Since about 15000 million years, the universe was very small and very hot. Through the Big Bang, the process of expansion and changing started and it continues to this day. Within minutes of the explosion, the atomic particles merged together producing helium and hydrogen which over the years produced galaxies, stars and the universe as we know it today.

Stages of the origin of the universe since Big Bang:The Big Bang The process of expansion

and changing of the gaseous ball components stared and it continues to this day

After explosion Temperature was about 1000000 million degrees

Within minutes The universe was formed containing 75% hydrogen and 25% helium.

After 1000 million years of the Big Bang.

Matter got joined in masses

within 2000 to 3000 million years of the Big Bang

Ancestral galaxies were evolved

After 3000 million years after the Big Bang.

Galaxies began to form

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Revision 3rd prep 1st term after 5000 million years of the Big Ban

Our galaxy, the Milky Way, took its disc form

after 100000 million years of the Big Bang

The Sun was born and then the Earth and planets were created.

after about 12000 million years of the Big Bang

Earliest life forms began to appear on earth

15000 million years after the Big Bang

The universe as it now

So, we can define the Big Bang as follows:

Big Bang: - it is a massive explosion happened, since 15000 million years,

resulted in it all forms of matter, energy and time.Or.

- it is the expansion of the universe and merging of atomic particles forming helium and hydrogen gases.

Enriching Information In 1964, scientists coincidently discovered radio waves coming from space. They concluded that these waves are a type of the echo coming from the Big Bang. T.V sets can receive such signal on the Earth.

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Future of the universe Scientists have different theories about this subject.

the opened universe theory the closed universe theoryThe scientists see that there is no definitive end to the universe

believe in see that the universe will stop expanding and will begin to contract until it becomes very compact or very hot, preparing for a new Big bang.

The Solar System

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Revision 3rd prep 1st term Millions of years ago, planets were originated in orbits around the sun to form what is known as the solar system.

The solar system The system consists of:

- the sun - Eight planets - Comets - Asteroids- Moons

** the planets and the other bodies were originated in solar system since 4600 million years ago.

** solar system extends over 12000 million km. in the space. ** sun is the center of solar system and it is the dominant body (total mass 99% of solar system)

Gravity in the solar system

Newton was the first one who discovered the earth's gravitational force.

The law of gravitation explain two points:

** the movement of planets around the sun. ** the movement of the moon around the earth.

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Newton’s law of universal gravitation.The force of attraction between two bodies is directly

proportional to the product of their masses and is inversely proportional to the square of the distance between them.

Then he proved that the gravitational force makes: 1 – Planets revolve around the sun in fixed orbits. 2 – The matter of each celestial body remains firm.

** if the gravitational force of celestial body was strong enough, it will attract gases towards itself forming atmospheric envelope around it.

** law of universal gravitation is one of the basic laws of the universe.

Question What happens if there is no attraction force between the sun and

earth? The earth will leave its orbit and float in random fashion in space and this will lead to destruction of the earth.

Exercise 1 – The metal sphere represents the planet. 2 – The hand represents the sun 3 – The thread represents the gravitational force. 4 – The path of the metal sphere represent the orbit.

Enriching information

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Revision 3rd prep 1st term ** Gravity keeps planets in their orbits around the sun and moons in their orbits around the planets.

** the effect of gravity decreases by increasing the distance between the sun and the planet.

WeightlessnessThe continuous force of the

Earth’s gravity on our bodies gives us weight.

But, when you are inside a lift going downward fast, you feel that you are lighter in weight.

weightlessness occurs in the spacecraft as astronauts fall down inside it with the same speed so that they get weightless.

Note If the lift falls (when the wire are cut) , you feel weightlessness.

Experiments are performed on both animals and plants in space to study the effects of weightlessness on them. Also,

specific scientific experiments are done as they cannot be done on surface of the Earth.

Theories about the evolution of the solar system

There are many scientific and philosophical theories about the evolution of the solar system. They are about twenty theories

These theories (as we shall see) are still unproved and subject to change.

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Revision 3rd prep 1st term Astronomers think that the most widely accepted model for explaining the formation and evolution of our solar system is " the Solar Nebular Model" which states that :

** planets and other bodies were originated in the solar system from the matter that remained from the evolution of the sun as follow:

1 – the sun was surrounded by solar nebula which is a sphere of gases and dust.

2 – the solar nebula stated to rotate.

3 – during rotation , it turned into a flat rotating disk.

4 – most of the dust compressed forming four masses. ((mercury, Venus, earth and mars ))** some dust and ice combined with gases forming (( Jupiter, Saturn, Uranus and Neptune))

Solar nebulaIt is a sphere of gases and dust from which the planets of the solar system were originated.

Most important theoriesNebular theory Crossing star theory Modern theory

1- Nebular theory (Laplace 1796)

assumption has been affected by two observations.

1 -There is something that looks like clouds or nebula in the space.

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Revision 3rd prep 1st term 2 -The space contains many cloudy rings surrounding some planets such as rings of Saturn.

Assumptions of nebular theory: The solar system was a glowing gaseous sphere revolving around

itself. This sphere is called nebula.

1 – the Nebula (glowing gaseous sphere) -Over the time, the nebula gradually lost its heat so its size contracted and its revolving speed around itself increased.

2- The gaseous rings

a. Under the effect of centrifugal force, the nebula lost its sphere form and became in a form of a flat rotating disk.

b. Parts got separated from the flat rotating disk to form gaseous rings that also rotate in the same direction in which the nebula rotates.

3-the formation of the solar system - These gaseous circles were formed after the planets of the solar system got cooled and frozen.

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Revision 3rd prep 1st term - The flaming mass that remained in the centre formed the

sun.-

Nebula: It is a glowing gaseous sphere revolving around itself, from which the solar system was originated.

2- The crossing star theory (Chamberlain and Molten 1905)

The crossing star theory is based on some assumptions:The solar system was originally a big star which is the sun.

1- huge star approached the sun. 2-This star attracted the sun to it; an act which led to a great expansion in the part of the sun facing it. 3-This expanded part was exploded which led to: ** a gaseous line was formed of a great length from the sun ** The sun escaped from the gravity of that star due to the explosion.

4-The gaseous line started to condense due to the attraction forces and then it cooled forming the planets.

The sun escaped from the gravity of the crossing star?

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Revision 3rd prep 1st term Due to the explosion of the expanded part of the sun.

3- The modern theory of the world (Alfred Hale, 1944)

This theory is based on - What is sometimes seen when a star glows for a short time to be one of the most shining stars in the sky.

- After a day or two, its glow disappears gradually to return as it was.

- The reason for that glow is not precisely known.

- It may be due to the explosion of the star as a result of nuclear reactions that occur so suddenly and violently that the star bombs huge amounts of gaseous materials. - Then, its size increases and accordingly its shining increases as well.- When the bombed gases are cooled, its shining returns as it was.

Assumptions of Alfred Hale (modern theory)

The solar system was originally a star rather than the sun:

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1-The existence of a star rotating near the sun

2-The star was exposed to explosion due to huge nuclear reactions.

3-The force of the explosion led to- the bombing of the star’s nucleus away from the gravity of the sun.-A cloud of gas remained

4 –the gaseous cloud subjected to cooling and contraction processes forming the matter of planets

5 – The attraction force of the sun controlled the orbits of planets around it.

The difference in the length of the day and year from a planet to another The earth revolves around its axis in a period of time estimated at one earth day, and it revolves around the sun in a period of time estimated at one earth year.

Earth's day It is the time taken by earth planet to complete one rotation around its axis.

Earth's year It is the time taken by earth planet to complete one rotation around the sun.

Note - earth's years = 365.25 earth's day. - The earth's day = 24 earth's hour.

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☼ 1 – Factored led to the difference in the length of the day: 1 -Radius of the planet earth.2 - Speed of the planet rotation around its axis.

Day it is the period taken by the planet to make one complete rotation around its axis.

2 – Factors led to the difference in the length of the year; 1 -Distance between the planet and the sun.2- Speed of the planet rotation around the sun

Yearit is the period taken by the planet to make one complete rotation around the sun.

Activity:>>> Explaining the difference in the length of the year from a planet to another.

Observation At equal speed, the time that each student takes to make a complete rotation increases as the distance between the student and centre increase

ConclusionThe difference length of a year is due to:1-Distance between the planet and the sun.2- Speed of the planet rotation around the sun.

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Revision 3rd prep 1st term Compared to the rest of planets of the solar system, astronomers managed to determine the day and year for each planet in terms of the earth day and year as shown in the following table

We can conclude that:The longest day is on Venus The shortest day is on Jupiter The longest year is on Neptune The shortest year is on Mercury

Science , technology and society

Space suit:- The first astronauts wore one space suit for the trip.- Today, they wear clothes that differ due to missions they perform. - There is a space suit to travel back and forth. - There is also a normal type of special clothes to be worn inside the spacecraft in its rotation.

The important instruments to study the outer spaceSpecial Equipments centered on earth and space in order to study the Sun.

1 – The solar telescopePlace : centered on the earth. Use : forms a picture of the sun.

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Revision 3rd prep 1st term This type of telescope works on reflecting the sun rays downward to a mirror in a tunnel under the Earth’s surface.

- the sunlight is gathered , then separated into a solar spectrum by the spectrometer(( device that shows the different light waves of the sun.))

- Astronomers got most of their information about the sun from the study of its spectra.

- a picture of sun is formed in a monitoring room where astronomers can study its light.

Modern equipmentsAstronomers use modern equipments on the surface of the Earth.

They also send them to space to get photos and information better than what surrounds us.

2- Telescopes

Telescopes rotating in orbits around the Earth are better than that are been on surface of the earth because :

- They can see celestial bodies more clearly. - They catch rays that can't be able to penetrate the earth's

atmosphere.

Examples:

The Hubble telescope- The Hubble telescope was launched in April in 1990 .

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Revision 3rd prep 1st term - It rotates around the earth at a height of 500 km. From its location, - it collects photos since millions of years .These photos allow astronomers an opportunity to study the evolution of the universe after the Big Bang. - Astronauts on a space shuttle regularly maintain this telescope in space.

3 – spacecrafts: They revolve around other planets or land on them, sending discoveries to the earth.

Most telescopes and spacecrafts are controlled by computers from he surface of the earth.

the importance of cell division process to living cell organisms?

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Multicellular organism’s bodies contain two types of cells: somatic cells and reproductive cells. Each type is divided in a special way.

Cells in multicellular organisms are divided in different ways to achieve different purposes:

1- Somatic cells are divided by mitosis which leads to the growth of living organisms and compensation of the damaged cells.

Examples of somatic cells: - cells of ( liver, skin , kidney , ….. ) in human and animals. - cells of ( roots, stem, leaves, …… ) in plant.

2- Reproductive cells are divided by meiosis which leads to the formation of male and female gametes

Examples of reproductive cells: - testis and ovary cells ( in human and animals ) - Anther and ovary cells (in flowering plants).

Which part of the cell is responsible for cell division? Neculus which contain Chromosomes have the main role in cell division.

General structure of the chromosome :

1- The chromosome consists of two connected threads at the centromere point each thread is called a chromatid.

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2-The chromosome chemically consists of nuclear acid called D.N.A and protein.

3- Centromere it is the point of connection the two chromatid

Chromosomes: They are thread like bodies present in cell's nuclei and they represent the genetic material of the living organism.

Centromere;It is the point of connection of the two chromatids of chromosome during the cell division.

Chemical structure: Each chromatid consists of:

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Revision 3rd prep 1st term - a nucleic acid called (DNA) which carries the genes that

carry the genetic traits of the living organism.

- Protein.

DNA It is the nucleic acid that forms the chromosomes that present in the cell nucleus and it carries the genes.

The cell Nucleus chromosomes Genes

Information about chromosomes: The number of chromosomes in living organisms is:

** Different from species to another. ** fixed in members of same species.

Organism No of chromosomes

Human 46Rabbit 44Mosquito 6Fly 12Onion 16

Enriching information: Somatic cells in most living organisms contain two sets of chromosomes (one inherited from the father and the other inherited from the mother) known as the diploid number (2N),while the gametes (male gametes (sperm) female gametes (ovum) contain the haploid number (N). ** Knowing the number of chromosomes helps in identifying the animal and plant species

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It is a complicated process through which the living cell divides into two cells more to aim the growth or reproduction.

1 – Mitosis

First: MitosisMitosis occurs in the somatic cells of organisms such as:

all body cells except reproductive cells and neural cells. Cells of roots , stems and leaves (in plants).

Importance : it plays an important role in: growth of living organisms compensation of the damaged cells. Competing the asexual reproduction process.

.** the cell passes through a phase called interphase before mitosis.

During interphase: the cell prepares for division the amount of genetic material (DNA) duplicates.

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Cell division

Types of cell divison

2 - Meiosis


Phases (stages) of mitosis: DrawingEvents

1-Chromatin reticulum intensifies and appears in the form of long, thin and double strings (chromosomes).

الخيطية األليافspindle is composed extending between the two poles of the

3-The spindle fibres in the animal cell is formed from the centrosome In the plant cell, the spindle is composed from intensifying the cytoplasm at the cell poles.4-At the end of this phase, the nucleolus and nuclear

Prop

hase

The chromosomes are arranged along the cell equator where each chromosome is connected with one of the spindle fibers

Met

apha

se

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Revision 3rd prep 1st term 1-Centromere of each chromosome splits lengthwise into two

Chromatids in each chromosome then separate from each

2-Spindle fibers begin to shrink and two -identical groups of chromatids are formed. Each group

Anap

hase

a series of adverse changes occur which lead to the formation of a complete set of chromosomes that have the same number of the mother cell’s chromosomes. Nuclear threads, a nuclear network and then two new separate cells are formed. Each cell has the same number of chromosomes

3-Te

loph

ase:

Note Changes in Telophase are called the adverse changes in prophase stage

How many chromosomes are there in the parental cell resulted from mitotic cell division?Both of them (2N)

Science , technology and society Liver transplantation:

Liver cells are not divided in normal conditions but retain the ability to divide under certain circumstances.

For example, if the liver gets injured or a part of it is cut, the remaining cells undergo many mitotic divisions to compensate the missing part. This is the scientific basis used in liver transplantation.

*** Some cells in human body are not divided at all such as nerve cells and red blood cells.

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Second: Meiosis Meiosis occurs in living organisms that reproduce by gametes.

Occurrence : * In humans and animals, Its important this division occurs in the testis ةto produce the male gametes (sperms) and in the ovary to form the female gametes (ova).

* In flowering plants this division occurs in the anther to produce the pollen grains and in the flower ovary to form an egg.

Importance : production of male gametes and females gametes to complete the sexual reproduction.

*** before starting meiosis, the cell passes through interphase where chromosomes are doubled.

Phases of meiosis: 1 – First meiotic division 2 – Second meiotic division.

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First meiotic division Prophase 1 , Metaphase 1 , Anaphase 1 and Telophase 1

Prop

hase

IM

etap

hase

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Ana

phas

e 1

Telo

phas

e:

The crossing over phenomenonAt the end of prophase I, some parts of the two inner

chromatids of each tetrad are exchanged to produce new genetic arrangements. This process is called the crossing over phenomenon.

Crossing over phenomenon

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Revision 3rd prep 1st term It is a phenomenon that takes place at the end of prophase 1 and in which some parts of the two inner chromatids of each tetrad are exchanged to produce new genetic arrangements.

What is the importance of the crossing over phenomenon?It contributes in genes (that carry genetic traits) exchanging between the two homologous chromosome's chromatids and distributing them randomly in the gametes, causing genetic variation.

Second meiotic division:It aims to increase the number of produced cells. Each cell is called the (gamete), containing half the number of species chromosomes. Each cell of the two cells which resulted from the first meiotic division is divided in a way similar to mitosis division phases.

In the final phase (telophase II) of this division, four cells are produced and each of them contains half the number of chromosomes of the parent cell.

When the male gamete combines with the female gamete, the zygote is formed. It contains the original number of the organism’s chromosomes. Thus, the number of chromosomes remains constant in the cells of members of the same species.

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Science , Technology and society

Enriching Activity >> preparing a slide from growing tip of onion's root To different phases of mitotic cell division.

Procedures:

Nanotechnology and cancer treatment:

Cancer occurs when the body cells are divided continuously without controlling.

- the mass resulted is called tumor - Egyptian Scientist Dr. Mustafa El Said discover a Nano-

molecules which kill this tumor called Nanotechnology that we benefit from it in:

1 – Discovering cancer disease:

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Revision 3rd prep 1st term - This technic starts by loading certain type of protein with

nano-molecules of gold and then injecting them into the patient.

- Proteins attach on the cancerous cell surface to monitor it through a microscope.

2 – Treatment of cancer: A. by using Nano-molecules of gold as follows:

- Focusing laser with a certain degree to the gold molecules, then the gold molecules absorb the light and convert it into heat which burn and kill the infected cell.

B . by using developed microscopic bombs:

- Scientists have developed smart microscopic bombs that penetrate the cancer cells and explode them from inside.

- They were used to kill the cancer cells in an experimental mice .

- Treated mice live 300 days while non-treated ones live 43 days only.

Reproduction process: It is a biological process where the living organism produces new individuals of same kind to ensure its continuity.Importance of Reproduction: to produce new individuals.Types of Reroduction: Asexual and sexual Reproduction.

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Revision 3rd prep 1st term Asexual By one organism (single celled as yeast and amoeba)

Sexual By two organisms(male and female) as plants and animals

Types of asexual reproduction((Binary fission / Budding / Regeneration / Spore propagation / Vegetative reproduction))

Binary Fission It occurs in unicellular organisms (amoeba / paramecium/ Euglena/ simple algae / bacteria

Budding it occurs in unicellular as yeast, and in multicellular organisms as hydra and sponges.

Reproduction by budding/ it is asexual reproduction produces new individuals by formation of buds in the parent cell.

Regeneration: it is the ability of animals to compensate their missing parts.

It occurs in some animals like starfish with parts that contain central disc.

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Asexual ReproductionIt is a process by which living organisms produce new individuals with genetic traits identical to those of their parents.


Sporogony (spore propagation) it occurs in bread mould, mushrooms and some algae.

Vegetative Reproduction it occurs in plants (leaves, roots and stems), and in tissue culturing (mitotic division)

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Vegetative Reproduction / it is an asexual reproduction by using vegetative organs except seeds.

Second / Sexual reproduction

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Sexual ReproductionIt is a process by which living organism produces individuals with traits differ from parents.

It occurs between male and female

And depend on two main process1- Gametes formation (sperms and ovum) which contain half number of chromosomes

N

2- Fertilization that means combination of male and female gametes to form zygote.

The ZygoteIt is a cell produced due to fertilization

Note Sexual reproduction is a source of the genetic variation from parents to children.

My best wishes,

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rodynaspirt.files.wordpress.com€¦ · Web viewThe motion:-it is the change of object's location as time passes according to the location of another object. Speed . is a physical