MotionMotion

MotionMotion

change in positionchange in position

TPS: List three examples of motion.TPS: List three examples of motion.

Be prepared to explain.Be prepared to explain.

How do I know if something is in How do I know if something is in motion?motion?

Reference pointReference point is a place or object is a place or object used for comparison to see if used for comparison to see if something is in motion.something is in motion.

Reference Points

ForcesForces

A force is a push or pullA force is a push or pull

In your notebook list at least 4 examples of force

Be prepared to share your answers

Balanced and Unbalanced ForcesBalanced and Unbalanced Forces

To describe a force, you must know two To describe a force, you must know two things:things:

SizeSize of the force and of the force and DirectionDirection of the force of the force

Balanced ForcesBalanced Forces

Forces that are equal in size but Forces that are equal in size but opposite in directionopposite in direction

Balanced forces do Balanced forces do notnot cause a change in cause a change in the motion of objectsthe motion of objects

Unbalanced ForcesUnbalanced Forces

Forces that cause a change in the Forces that cause a change in the motion of an objectmotion of an object

Balanced or Unbalanced?Balanced or Unbalanced?

Explain your answer

45 N 45 N

50 N 50 N

Unbalanced forcesUnbalanced forces

Unbalanced forces can change the Unbalanced forces can change the motion of an object in two ways:motion of an object in two ways:

When unbalanced forces act on an When unbalanced forces act on an object at rest, the object will moveobject at rest, the object will move

When unbalanced forces act on a When unbalanced forces act on a moving object, the velocity of the object moving object, the velocity of the object

will changewill change

WorkWorkWorkWork: using a force : using a force

for a distance for a distance

W = F x d W = F x d

The work done by forces on an The work done by forces on an object = changes in energy for object = changes in energy for that object.that object.

Work and Energy are Work and Energy are measured in Joules measured in Joules

1 Joule=1 Newton • meter1 Joule=1 Newton • meter

42 42 How much work is performed when a 50 kg How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N?crate is pushed 15 m with a force of 20 N?

FF 300 J 300 JG G 750 J750 JH H 1,000 J1,000 JJ J 15,000 J15,000 J

Use the formula Work = Force x distance

Force of 20 N x 15 meters = 300 Joules Answer:

EnergyEnergy

Is defined as the Ability Is defined as the Ability to do Workto do Work So something has energy if it has the ability to do So something has energy if it has the ability to do

work.( move an object over a distance in the work.( move an object over a distance in the direction of the force)direction of the force)

No work: movement is forward, but force on books is upward

Work: movement of nail is in

direction of force

SpeedSpeed

distance traveled per unit of timedistance traveled per unit of time

speed = distance / timespeed = distance / time

Calculating SpeedCalculating Speed

Distance= Speed X Time

Speed = Distance Time

Time = Distance Speed

Write these in your notebook

Which formula?Which formula? Work with a partner to decide what formula you Work with a partner to decide what formula you

would use with each of these problems:would use with each of these problems:

A car drives 30 miles in 2 hours. A car drives 30 miles in 2 hours. Calculate the car's speed.Calculate the car's speed.

How far would you travel at 80 km / hr How far would you travel at 80 km / hr for 5 hours?for 5 hours?

How long would it take to go 250 miles How long would it take to go 250 miles at a speed of 50 miles / hour?at a speed of 50 miles / hour?

Be prepared to share your answersBe prepared to share your answers

Demonstrate that changes in motion Demonstrate that changes in motion can be graphically represented can be graphically represented

What does it show?What does it show?

Firstly, look at the axis to see what the graph represents.

Drawing graphs of real-life situationsDrawing graphs of real-life situations

In your exams you may be asked to complete, or draw, graphs to represent given situations.

Plot a distance time-graph to represent your journey to and from the club.

You are at home getting ready to go out to your stamp collecting club.

You leave your house and jog the 1000m to the club. You arrive 5 minutes later.

You exchange stamps and chat for 1 hour, then leave for home. It takes you 10 minutes.

Example 1.

1. Choose a suitable scale for each axis.

You are at home getting ready to go out to your stamp collecting club.

You leave your house and jog the 1000m to the club. You arrive 5 minutes later.

You exchange stamps and chat for 1 hour, then leave for home. It takes you 10 minutes.

Distance from home

(m)

Time (minutes)

200

400

600

800

1000

0 10 20 30 40 50 60 70 80

2. Decide how many points to plot.You are at home getting ready to go out to your stamp collecting club.

You leave your house and jog the 1000m to the club. You arrive 5 minutes later.

You exchange stamps and chat for 1 hour, then leave for home. It takes you 10 minutes.

3. Draw the graph with suitable accuracy

4. Provide a title and label the axis

The journey to and from my stamp collecting club

Drawing graphs of real-life problems

VelocityVelocity

Speed and directionSpeed and direction

Velocity describes the speed and direction of a Velocity describes the speed and direction of a moving objectmoving object

Speed or Velocity?Speed or Velocity? Read the following and work with a partner to decide if Read the following and work with a partner to decide if

the following represent “Speed” or “Velocity”the following represent “Speed” or “Velocity”

airplane moving towards the west with a airplane moving towards the west with a speed of 482 km/hrspeed of 482 km/hr

car moving at 80 km/hrcar moving at 80 km/hr

Be ready to explain your answersBe ready to explain your answers

Changes in SpeedChanges in Speed

Speeding up and slowing down are Speeding up and slowing down are changes in speedchanges in speed

AccelerationAccelerationChange in speed or directionChange in speed or direction

An object is accelerating when it speeds up, An object is accelerating when it speeds up, slows down, or changes directionslows down, or changes direction

AccelerationAcceleration

3 Examples:3 Examples:Case 1 – Interval Case 1 – Interval increases because car is increases because car is moving faster and fastermoving faster and faster

Case 2 – Interval Case 2 – Interval decreases because car is decreases because car is slowing downslowing down

Case 3 – Interval stays Case 3 – Interval stays the same, but direction of the same, but direction of motion is constantly motion is constantly changingchanging

AccelerationAcceleration

Slowing down is sometimes called Slowing down is sometimes called decelerationdeceleration

TPS: work with a partner to TPS: work with a partner to explain why coming to a stop at explain why coming to a stop at

a traffic light is acceleration.a traffic light is acceleration.

Be ready to share your answerBe ready to share your answer

Newton’s First Law of MotionNewton’s First Law of Motion

Newton’s First Law of Motion states Newton’s First Law of Motion states that an object will remain at rest, or that an object will remain at rest, or

move at a constant speed in a move at a constant speed in a straight line, unless it is acted on by straight line, unless it is acted on by

an unbalanced forcean unbalanced force

Newton’s First Law of MotionNewton’s First Law of Motion

inertiainertia – tendency of an object to stay – tendency of an object to stay at rest or in motionat rest or in motion

Newton’s First Law of Motion is also called Newton’s First Law of Motion is also called the the Law of Inertia

Watch this animation, then TPS to explain Watch this animation, then TPS to explain why is it important to wear seatbelts when why is it important to wear seatbelts when

riding in a car. riding in a car.

Be prepared to share your thoughts with the Be prepared to share your thoughts with the class.class.

After watching the film clip, quickly sketch this drawing in After watching the film clip, quickly sketch this drawing in your notebook.your notebook.

Add a seatbelt to the driver. Add a seatbelt to the driver.

Use another arrow to show the force that the seatbelt Use another arrow to show the force that the seatbelt exerts to prevent the man from flying out of the carexerts to prevent the man from flying out of the car

Newton’s First Law in action!

Now check your sketch by Now check your sketch by watching this film clip:watching this film clip:

Car Crash

Do you need to make any changes to your sketch?

If so, do it now.Write a paragraph to describe how seatbelts and

car crashes are related to Newton’s First Law of Inertia.

Newton’s Second Law of MotionNewton’s Second Law of Motion

Newton’s Second Law of Motion describes the relationship among describes the relationship among forceforce, , massmass, and , and accelerationacceleration

Watch this clip and then TPS to Watch this clip and then TPS to explain what can cause the elephant explain what can cause the elephant

to move faster.to move faster.

Newton’s Second Law of MotionNewton’s Second Law of MotionUnbalanced forces cause objects to Unbalanced forces cause objects to

accelerateaccelerate

The amount by which an object The amount by which an object accelerates depends on two thingsaccelerates depends on two things

SizeSize and and directiondirection of the force of the force

Mass Mass of the objectof the object

Newton’s Second Law of MotionNewton’s Second Law of MotionIf two forces act on the same object, If two forces act on the same object, the larger force will produce more the larger force will produce more acceleration than the smaller forceacceleration than the smaller force

Newton’s Second Law of MotionNewton’s Second Law of MotionIf you apply the same amount of force to If you apply the same amount of force to

two objects with different masses, the two objects with different masses, the object with the smaller mass will object with the smaller mass will

accelerate more than the object with the accelerate more than the object with the larger masslarger mass

TPS to discuss:TPS to discuss:How can you apply a force to two objects with How can you apply a force to two objects with

different masses, but still have them accelerate at different masses, but still have them accelerate at the same rate?the same rate?

Newton’s Second Law of MotionNewton’s Second Law of Motion

force = mass X accelerationforce = mass X acceleration

F = m x a

Force is measured in Newtons (N)Force is measured in Newtons (N)

Newton – unit of force equal to one Newton – unit of force equal to one kilogram-meter per second per secondkilogram-meter per second per second

Newton’s Third Law of MotionNewton’s Third Law of Motion

Newton’s Third Law of Motion states Newton’s Third Law of Motion states that for every action force, there is that for every action force, there is

an equal and opposite reaction forcean equal and opposite reaction force

Newton’s Third Law of MotionNewton’s Third Law of Motion

Forces always act in pairsForces always act in pairs

The two forces act in opposite The two forces act in opposite directionsdirections

Newton’s Third Law of MotionNewton’s Third Law of Motion

action force – force acting in one action force – force acting in one directiondirection

reaction force – force acting in the – force acting in the opposite direction (scroll down to opposite direction (scroll down to

boat boat animationanimation))

Watch the animation, then TPS to Watch the animation, then TPS to explain why the boat moved away explain why the boat moved away

from the dock.from the dock.

Review Review Match the following to the Newton’s LawMatch the following to the Newton’s Lawthat explains the motion in each picturethat explains the motion in each picture

1St Law ?2nd Law?

Or3rd Law?