Unit 6 PS

Standard PS 5

Copy down the Speeds of AnimalsMAKE A BAR GRAPH WITH THESE ANIMALS AND

THEIR SPEEDS ON IT Animal Name on X axisPig 11 mphMouse 8 mphSix-lined race runner 18 mphElephant 25 mphMoose 35 mphLion 50 mph

Drill Panther

BAR GRAPH

Panther Drill

Copy this equation: This how to figure out your speed in miles per hour

75 ft X 1 mile X 3600 secyour 5280 ft 1 hr

Your SPEEDSpeed = Distance divided by time

For us today:

ft/sec

Unit 6 Motion

Motion: movement of an object from a fixed point.

Fixed point is called the reference point (this is the starting line)

Distance Distance how far something has moved. IE How far

you drive in your car. It is only a number or amount.

For instance LCHS is exactly 61.3 miles from my door to the parking lot. This is distance.

DisplacementDisplacement: is a distance and a direction. For

example to get to the deer stand in the woods I had to walk 1500 yards North west from the road.

Total or Final Displacement: change in position from the starting point.

LOOK AT EXAMPLE ON THE NEXT SLIDE

Total displacement You travel:

6 miles east then

3 miles west6 miles E

3 miles W

Total displacement (distance from where you started) = 6 miles – 3 miles = 3 miles. You am now 3 miles from your house.

Panther Drill

What is the difference between speed and velocity?

SpeedSpeed: the distance traveled per unit of time.

Speed (s) = distance (d)/time (t) s=d/t meters/sec

Different speeds

Cruise control on a empty road= constant speedBumper to bumper traffic = changing speed, your

speed is fast, then slower, then faster, then slower ect

Speed and Velocity Speed: we already know is the distance

traveled in a given unit of time. Measured for science in meters per second. Can also be mph

Velocity: speed with direction 22 m/sec SE IE: You have to walk 2.8 mph NW from the road into the woods to the deer stand.

Hurricane Fran 1996

You are here

Who cares? You should. The red case means your butt could be toast!!! Hurricane coming right at us!!!!!!

Speed = 22 mph

Velocity = 22 mph North East

Speed = 22 mph

Velocity = 22 mph NorthWest

The purple case velocity means surfs up dude!!!

Different speedsConstant Speed: when speed is unchanged. like

cruise control in the car.

Changing speed: speed is not constant or consistent. Like stop and go traffic.

Average Speed: used when speed is changing, = s (avg) = Total Distance Traveled

Total time spent traveling

Different speeds 2Instantaneous Speed: Speed at any given time, only

true at that instant it is observed.

Instantaneous SpeedFerrari Enzo 0-60 time 3.3

secs. The speed at any time over that 3.3 seconds would be

different.

Exit

Explain the difference between speed and velocity.

Panther Drill

If the formula for speed is s=d/t, write down how to find distance and how to find time, using the same equations.

t = d/s

d = sxd

Vid Clip

VIDEO

Acceleration

Acceleration: (a) the rate of change in velocity per unit of time

Original or Initial Velocity= 20 m/secFinal velocity = 80 m/sec Time = 2 sec

Acceleration = Velocity(final) - Velocity(original)

time

80m/s – 20m/s2 sec

a =

30 m/sec60m/s / 2 sec

a =

Acceleration =Velocity(final) - Velocity(original)

time

A car traveling at 60 mph accelerates to90 mph in 3 seconds. What is thecar’s acceleration?

=90 mph - 60 mph

3 seconds

=30 mph

3 seconds

= 10 mph/second

Acceleration Units

The Unit for Acceleration in science is meters per second per second or m/s2

a = V final – V Initial m/s time s

Panther Drill

If you are traveling at 4 m/sec and then speed up to 12 m/s in a period of 5 seconds. What is your acceleration

Tuesday 2/15

Panther Drill

1 2 3 4 5 6 7 80

2

4

6

8

10

12

14

16

18

Velocity in m/s

Seconds

Use the graph to find out what is the acceleration between 3 seconds and 7 seconds

Extra Credit: What is the slope of the line?

PD Answer

Acceleration (a) = Vf – Vit

time = 7 sec – 3 sec = 4sec

14 – 6 = 8/4 = 2 m/s2

4

Vf = 14 m/s

Vi = 6 m/s

Extra Credit

Slope: m= (y1-y2)

(X1-X2)

3 – 7 =6-14

-4/-8 m = 2

??QUESTION??

Is the acceleration changing when you look at the graph?

At what kind of rate, changing or constant?

What do you see when you compare the slope with the acceleration?

They are =

Slope of the line = the acceleration!!!!

Yes

Constant

ExampleJoval and Justice pull up to each other at a stop

light. They decide to race. The 2 cars accelerate as a traffic light turns green. In 5 seconds, Joval (car 1) goes 0-40km/hr and Justice (car 2) goes 0-50 km/hr. Which car accelerates the fastest?

Car 1: Given: Useful Equations

Unknown Substitute

Evaluate Answer

Joval’s Car: Given:

WHAT IS GIVEN IN THE PROBLEM

Useful Equations

Unknown

WHAT DO YOU NEED TO FIND OUT?

Substitute

Evaluate Answer DOES THIS MAKE SENSE?

t

vva if

Car 1: Given:

Time: 5 secVi: 0Vf: 40

Useful Equations

Unknown

ACCELERATION

Substitute

HERE YOU WOULD do calculations

Evaluate Answer DOES THIS MAKE SENSE?

t

vva if

Car 1: Given:

Time: 5 secVi: 0Vf: 40

Useful Equations

Unknown

acceleration

Substitute

a= (40 km/hr-0 km/hr) 5 sec

a = 40/5 = 8 km/hr/sEvaluate Answer DOES THIS MAKE SENSE?

YES

t

vva if

Car 1: Given:

Time: 5 secVi: 0Vf: 40

Useful Equations

Unknown

acceleration

Substitute

a= (40 km/hr-0 km/hr) 5 sec

a = 40/5 = 8km/hr/sEvaluate Answer DOES THIS MAKE SENSE?

YES

t

vva if

You do car #2

What is its acceleration?

Panther Drill

Define the following:1. Constant acceleration2. Changing acceleration3. Positive acceleration4. Negative Acceleration

Positive and Negative Acceleration

Positive acceleration: speeding up

Negative acceleration: slowing down

Velocity is still in the same direction

Acceleration

Velocity

Velocity

Acceleration

Positive acceleration

Negative acceleration

Graphing

The area in red is where constant velocity occurs.

Here there is 0 acceleration

1 2 3 4 5 6 7 8 9 100

5

10

15

20

25

Velocity m/s

Velocity m/s

Seconds

Changing Acceleration

In changing acceleration the graph is not a straight line with a constant slope.

Changing acceleration is speeding up or slowing down.

WorkLets check it: Vi = 22 Vf = 22 t = 7 (10-3 sec) 22-22 = 0/7 = 0m/s2

7

1 2 3 4 5 6 7 8 9 100

5

10

15

20

25

Velocity m/s

Velocity m/s

Seconds

Graphing

Draw a sketch of positive, negative, constant, and zero acceleration on graph paper. Label each sketch. Make sure you title the sketches and tell me what each axis measures.. Divide the graph paper in into quarters. Put each graph in a separate ¼ of the paper.

Exit Assignment

Circle the area where there is positive, negative, and 0 acceleration.

1 2 3 4 5 6 7 8 9 10 11 12 130

5

10

15

20

25

30

Velocity Vs Time

Velocity Vs Time

MondayStudents will construct time-distance graphsPS 5.6 Represent the linear motion of objects on

distance-time graphs.

Panther Drill

In your own words describeDistanceDisplacementSpeedVelocity

0 speed and 0 Acceleration

Constant Speed and Acceleraton

Positive (Changing) Acceleration

Negative Changing Acceleration

PRACTICEOn your graph paper graph the following data

Compare the speed of the 2 objects on a graph

Looks like this

Panther Drill

1 2 3 4 5 60

2

4

6

8

10

12

14DIstance Time

Describe what type of motion or motions that each graph shows

#1

1 2 3 4 5 6 70

2

4

6

8

10

12

14

16

VELOCITY

Time

#2

ANSWERS

#1) Increasing speed, Constant Rate Speed, would be acceleration if y axis = velocity and not distance

#2) Slowing down, negative and changing acceleration

Story Graph

A student walks 25 ft west in 3 secs Then the student stops and talks to his friends

for 5 secs.The student then walks 30 feet west in 6 secsThen the student realizes he will be late for class

and then walks a lot faster he travels 100 feet in 5 secs

Tues

Panther Drill

How does the force applied to an object affect its acceleration?

Lab pp 58 Text

Wednesday

Start Car LAb

Panther Drill

1. Write down a few sentences to describe what is happening in the graph. Similar to the graphing exercise yesterday.

1 2 3 4 5 6 7 8 9 10 11 12 130

2

4

6

8

10

12

14

DIstance

Time

PreviewWhat is a Force:

Push or pull on an object.Examples? Passing a Basketball or Kicking a soccer ball

Returning Serve in tennis matchStepping on the brakes Catching Line drive.

What affect to you think force applied to an object has on acceleration?

What affect to you think force applied to an object has on acceleration of the object?

When force is increased in the same direction as the acceleration, then the acceleration increases.

When force is applied or increased in the opposite direction acceleration will lessen.

When force is applied in another direction besides opposite, acceleration can change because the direction will change and acceleration is a measure of velocity and velocity includes direction.

Lab On THURSDAYGet a book and open to pp 58-59

Pre-Lab1) Write a hypothesis of what you think will

happen in the lab.2) List the 2 forces you will apply to the car to

change acceleration and how you apply those forces.

3) On a separate sheet of paper create a data table that looks like this.

Monday

Panther Drill

List 3 things you do to change a objects motion or acceleration

Force and MotionAs we know force is a push or a pull

We also know that forces cause movement.

Can an object have more than 1 force acting on it at 1 time?

What are some examples?YES

Net Force: the total of all forces action on an object

Force is represented in a diagram by an arrow. The arrow shows the direction the force is pushing or pulling

Net Force** Remember the force has a number (or

magnitude) and a direction**

When you have balanced forces, net force = 0.

How do you measure force?

Force is measured in NEWTONS

Newton: force necessary to provide a mass of one kilogram with an acceleration of one meter per second per second.

NEWTON = (n)

ForcesDoes applying a force to an object always change

velocity?

Like we just saw an object can have more than 1 force acting on it and not have the motion or velocity change.

Balanced forces: forces of equal size (amount or magnitude) acting on an object in opposite direction that cancel each other out.

10n 10n

What force acts on us all the time?GRAVITYGravity is always holding us down on the earth, and

the = force of the ground is pushing us back so we stay planted on the ground.

What is this an example of?BALANCED FORCES

Gravity pulls an object down, but the object is pushed up by the ground or floor it stands on, so the object does not move this is balanced forces.

Unbalanced forces: when 2 or more forces are action on an object that are unequal. The object will move in the direction that the stronger force is pushing it.

volunteers

Net Force** Remember the force has a number (or

magnitude) and a direction**

When you have balanced forces, net force = 0.

When you have unbalanced forces net force = a number other than 0, the number can be + or – and has a direction

Force DiagramsForce Diagram: the rectangle

represents the object being studied. The areas represent the forces acting on that object.

If you are jumping in the air, your legs produce a force to overcome gravity the force diagram would look like this:

900 N

588 N

F net= 412 N

Demo

Force Diagram

Since the object stopped going downward, the force applied to the object by the spring becomes = to the force of gravity

InertiaInertia: the tendency of an object to resist change in

its motion.

To get an object to change its motion or velocity a force needs to be applied to greater than the force that is already acting on it.

The larger the amount force that is needed to change the motion or velocity of an object the greater the inertia of the object.

Which on of these will require the strongest force to change its motion?

Bowling ballWhich on has the greatest inertia? Bowling ballWhich of these has the greatest mass? Bowling ball

The more mass an object has, the greater its inertia.

NEWTONS LAWSNewton’s 1st law of motion states: An object at rest

stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. ALSO KNOWN AS LAW OF INERTIA

Any body shoot pool?

Newton’s Law in ActionWhat forces are in the

break in a game of pool?

Cue stick-cue ballCue ball-Other ballsBalls hitting each

otherAre these forces

balanced or unbalanced

Unbalanced

How does this show the law of inertia?

The balls are resting until a greater force of the cue ball makes them move.

Tuesday

Panther DrillFinish Inertia (5)Pre-Video Quiz (5)Video w/ quiz (25)Post Video Sheet (10 min)Newtons 2nd law

Panther Drill

Describe the law of inertia.

Wed

Panther DrillFriction NotesFriction DemoStart Newton’s second law notesExit ticket

Panther Drill

1 Which of the following is a force?

A. AccelerationB. InertiaC. FrictionD. Velocity

2 Which of the following best describes an objects constant velocity

A. Its direction is changingB. Acceleration is positiveC. Acceleration is negativeD. Acceleration is zero

What force that is holding the block in place on the incline?

FRICTION

Friction: the force that opposes the motion or attempted motion of one surface across another surface.

To over come the force of friction and make the block move a stronger force must be applied to the block to create unbalanced forces.

The sticking together of microscopic bumps on an object. The “sticking together” are called micro-welds.

The larger the mass of the object the stronger the micro-welds, the more friction there is.

Friction depends on mass not contact or surface area

Friction What causes it?

FrictionWhere is the friction greater object A or B? WHY?

RAISE YOUR HAND DON’T CALL OUT

Lab table

2 kg3 kg

A B

3 KINDS OF FRICTIONStatic friction: “The frictional force that prevents to

surfaces from sliding over or past each other”

Stationary or still objects, basically what holds an object from sliding across surface when you push on it. The force you applied was not great enough to overcome the micro-welds.

Caused by the force pushing down and up on the object.

Micro-welds

Explains why more force was required to move the blocks once we added the bars in our demo.

3 KINDS OF FRICTIONSliding Friction: is the force that opposes the motion

of 2 surfaces past each other after static friction has been broken. Only on objects moving already. The force of sliding friction is in the opposite direction of the applied force.

Applied Force (push)

Sliding friction

More mass =More Friction

Sliding FrictionPush the book across the floor

Sliding friction occurs as the book’s surface moves across the floor. Sliding friction is the opposite force as your “PUSH”.

Will the book keep going if you stop pushing?NO, as the force pushing is stopped, sliding friction

slows then stops an object.Then static friction takes over.

Rolling Friction: The friction between a rolling object and the surface it rolls on.

The friction between the rolling tires and the ground is called rolling friction.

• • Rolling friction is much less friction than static or

sliding friction. That is why it is easier to use a dolly than pushing your kid brother in the box.

3 KINDS OF FRICTION

Start PD 4

Air Resistance• Acts on objects on objects that fall through

the air• The force of air resistance is in the opposite

direction to the force of gravity• Air resistance affects anything that moves in

earth’s atmosphere• Air resistance is pushing up as an object falls

due to gravity• Depends on speed, size and shape of object.

Air resistance

START PD 7

Terminal Velocity

• When the forces on the falling object are balanced and the object no longer accelerates

• When it falls with a constant speed called the terminal velocity

Thursday

Panther DrillSound Travels at a speed of 330 m/s. How long

does it take for the sound of thunder to travel 1485 meters?

A) 45 secondsB) 4.5 secondsC) 4900 secondsD) 0.22 seconds

SHOW WORK!!!!!!

s = d/ts= 330 m/sd = 1485 m

t= 1485m/330m/s

t= 4.5 seconds

t = d/s

Newton’s 2nd Law of motionForce and Acceleration

The other day we talked about Newton’s first law of motion that basically says that an objects motion can only change if an unbalanced force acts on it.

How is a 60 mph fastball different than a 95 mph fastball?

DUH the speed right? And the force it is thrown with.

Also the acceleration of the faster pitch is greater because its velocity changes more over the same distance

EVIDENCE a of 60 mph fastball:

Vfin = 60 mph Vin = 0 mph Distance = 60.5 feet.

60 – 0 / 60.5 = .99 m/h2

a of 95 mph fastball Vfin = 90 mph Vin = 0 mph Distance = 60.5 feet.

90 – 0 / 60.5 = 1.49 m/h2

Newton’s 2nd Law of motionMass and Acceleration

If you throw a baseball and shot-put as hard as you can (with the same force) will the move at the same speed?NO!!!WHY?The shot is much heavier (greater mass) and it requires much more force to make it move at the same speed as the baseballBaseball = .14 kg High School Shot = 4 kg

NEWTON’S SECOND LAW OF MOTIONNEWTON’S SECOND LAW OF MOTION: the

acceleration of an object is in the same direction as the net force acting on the object, and the acceleration can be figured out using the following formula: acceleration (in m/s2) = net force (in newtons)

mass (in Kg)

a= F net

m

You can use the formula to find net force or mass if you know the 2 other variables.

F net = m x a

m = F net

a

NEWTON’S SECOND LAW OF MOTION

F net = net force

a = acceleration

m = mass

Force CalculatedA rocket engine provides 28,913 Newtons of thrust.

The rocket has a mass of 2,350 kilograms. Calculate its acceleration if it moves HORIZONTALLY (we don’t want to fight gravity yet).

a= F net

m

28913 N 2350 kg

12.30 m/s2= =

YOU TRY1) Find the mass:

You push on a skateboard with a force of 10 N and it accelerates at 1.5 m/s2

What do you have given in the problem?a = 1.5 m/s2 & force 10 N What do you need to find?M = Fnet / a ; 10 N/ 1.5 m/s2 =

MASS6.67 Kg

Panther Drill

What is Newtons 2nd law?

If your net force is 25 newtons and your acceleration is .5 m/s2. What is the mass in kg of the object?

More

A truck accelerates at 10 m/s2 with a force of 1500 newtons. What is the mass of the truck?

Have: a & FnetNeed: massFormula: m = Fnet/aSolve: m = 1500/10ANSWER: 150 Kg

FridayProblems Newtons 2nd law

Tuesday

• Gravity

Panther Drill 3/8

Define gravity in your own words.

GravityGravity: an attractive force between any 2 objects,

that depends on the mass of the objects and the distance between them.

If the mass of one of the objects increases then the of attraction between the 2 objects increases.

Gravity

As the distance between 2 objects decreases then the gravitational force between them increases.

As the distance between 2 objects increases then the gravitational force between them decreases.

GravityNewtons Universal Law of Gravity:

(F) gravitational force = G x (m1 x m2)

d2

G is a constantm = massd = distance between the 2 objects.

The force of Gravity Lets figure out the force of attraction (gravity

between the earth and the moon

Distance between the 2: 384,403 kmMass of moon: 7.36 × 1022 kilogramsMass of earth: 5.9742 × 1024 kilograms

Set up the equation and we will do the math together.

Get w/ your partner

Each partner will do one of the questions and then explain their answer to their partner.

A/B partnerPartner A: The space shuttle launches at 5:00 am.

The gravity felt be the astronauts just before launch is 9.8 m/s2. How will the force of gravity felt be different 5 min after launch? Why?

Partner B: There are 2 identical satellites orbiting the earth, on at a distance of 120 Km (SAT. A)and on at a distance of 150 km (SAT B). Which satellite feels the earths gravity the strongest? Why?

Panther Drill

Two teams are competing in a tug-of-war contest. Team A is pulling at 4000N and Team B is pulling at 4900N is the opposite direction. Sketch the forces and show the net force exerted. Which team is winning? Is this force balanced or unbalanced?

Team A Team B

Rope4000N 4900N

g g

Ground pushing up

Mass

Definition: How much matter something containsAbbreviation: m How it is measured: with a balance.Unit: kilogram (kg) FOR THESE PROBLEMS MASS

IS ALWAYS IN KGHow to figure out mass (Newton’s 2nd Law: Fnet =

mass x acceleration) [Fnet = m x a]

Weight

• Definition: a force that combines (or puts together) mass and acceleration due to Gravity (ag) or also called the gravitational force on an object.

• Abbreviation: W• How it is measured: on a scale.• Unit: Newton (N)• How to figure it out: Weight (W) = mass (m) x

acceleration due to gravity (ag) [w=m x ag]

Calculations

Using the formula W = m x ag we can figure out weight or mass. g (gravity) always equals

9.8 m/s2 ,unless you are on another planet. To find weight multiply mass by gravity [w = m x

ag]

To find mass divide weight by gravity [m = w/ ag]

To find gravity, divide weight by mass [ag = w/m]

Thurs

Panther Drill

#1 What is the formula for determining weight?a) w= ag/m

b) w= ag x m

c) w= m/ag

# 2 If a stone has a mass of 14 kg and it is thrust down at the ground with 2 times the force of gravity, what would be the weight of the object as it fell.

280 N

Newtons 3rd Law

Remember that when there is an action, there is also a re-action.

Think about it like this; when you jump on a trampoline the trampoline exerts a force back at you.

Newtons 3rd LawNewton’s 3rd law says, that when 1 object exerts a

force on a 2nd object the 2nd object exerts a force that is equal and in the opposite of the 1st force.

For every action there is a an = and opposite reaction.

So with that being said, does that mean that the forces are balanced?

NO

Even though the forces are = they are not balanced because they are acting on different objects.

Think of a swimmer, as the swimmer moves forward the water pushes back but she still can move.

Example Lets tryVolunteers Need 2

1 sit in rolling chair and throw the ball HARD to the other person.

Look, the ball gets force exerted on it and moves, but you also move a little as the ball exerts a force on you.

Think of some other examples.

Main example

Rockets use Newton’s 3rd law, The engine exerts a force that

pushes hot gas out the back of the rocket, the gas exerts a force on the rocket and

LIFT OFF

What is your weight on other planets

Classwork

1. Get your mass in pounds, and convert it to Kg:Your wt in lbs = Your wt in Kg 2.2

256/2.2 = 116.362. Determine your mass: Your wt in kg

9.8116.36/9.8 = 26.12 kg (mass)

3. Determine your weight on other planets:

W = m x ag

Gravity on other Planets

Mercury: 3.73 m/s2

Venus: 8.93 m/s2

Jupiter: 24.92 m/s2

Neptune: 11.67 m/s2

Pluto (planetoid): .784 m/s2

Now that you have your mass figured out determine your weight on the planets above

w/ different gravity than on earth

Which Newton’s Law applies?A ball gets kicked and rolls along the ground. The ball

will continue to roll, at a constant velocity, unless something stops it.

1st lawYou are standing on a skateboard and push against a

wall? You roll in the opposite direction.3rd law

The fact that if you throw a baseball and softball with the same force the baseball will move faster.

2nd law

When you are traveling in a car and holding a cup of coffee and the driver slows down fast, and the coffee spills over the front edge of the cup.

1st – InertiaThe fact that the moon helps to influence the

tides on the planet and the earth keeps the moon from flying away.

Newtons law of gravity

When a soccer ball is sitting on the ground it will stay there until someone kicks it.

1st lawA train starts to pull a long line of boxcars that

were sitting at rest. Since the boxcars are so massive, they have a great deal of inertia and it takes a large force to change theirmotion. Once they are moving, it takesa large force to stop them?

1st lawThe more force hit the tennis ball with the faster

it will go2nd law

Fri

Panther DrillWhat is weight?a) Force an object exerts due to gravityb) The mass of an objectc) Acceleration due to gravity

What is the difference between static and kinetic friction?

a) Static friction holds in place, while kinetic friction only occurs when objects are moving.

b) Static and kinetic friction both resist movement, but static requires a stronger force to overcome

c) Both a and b.

Study Guide

Use the book and your notes to complete the study guide.