# Motion.

## Presentation on theme: "Motion."— Presentation transcript:

Motion

Motion change in position TPS: List three examples of motion.
Be prepared to explain.

How do I know if something is in motion?
Reference point is a place or object used for comparison to see if something is in motion. Reference Points

Forces A force is a push or pull

Balanced and Unbalanced Forces
To describe a force, you must know two things: Size of the force and Direction of the force

Balanced Forces Forces that are equal in size but opposite in direction Balanced forces do not cause a change in the motion of objects

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

Balanced or Unbalanced?

Unbalanced forces Unbalanced forces can change the motion of an object in two ways: When unbalanced forces act on an object at rest, the object will move When unbalanced forces act on a moving object, the velocity of the object will change

Work Work: using a force for a distance W = F x d
The work done by forces on an object = changes in energy for that object. Work and Energy are measured in Joules 1 Joule=1 Newton • meter

Use the formula Work = Force x distance
42 How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N? F 300 J G 750 J H 1,000 J J 15,000 J Use the formula Work = Force x distance Force of 20 N x 15 meters = 300 Joules Answer:

Work: movement of nail is in direction of force
Energy Is defined as the Ability to do Work So something has energy if it has the ability to do work.( move an object over a distance in the direction of the force) No work: movement is forward, but force on books is upward Work: movement of nail is in direction of force

distance traveled per unit of time
Speed distance traveled per unit of time speed = distance / time

Calculating Speed Write these in your notebook Speed = Distance Time
Speed X Time Write these in your notebook Time = Distance Speed

Which formula? Work with a partner to decide what formula you would use with each of these problems: A car drives 30 miles in 2 hours. Calculate the car's speed. How far would you travel at 80 km / hr for 5 hours? How long would it take to go 250 miles at a speed of 50 miles / hour? Be prepared to share your answers

Demonstrate that changes in motion can be graphically represented

What does it show? Firstly, look at the axis to see what the graph represents.

Drawing graphs of real-life situations
In your exams you may be asked to complete, or draw, graphs to represent given situations.

Example 1. 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. Plot a distance time-graph to represent your journey to and from the club.

Drawing graphs of real-life problems
Choose a suitable scale for each axis. 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. 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 200 400 600 800 1000 Distance from home (m) Time (minutes)

Velocity describes the speed and direction of a moving object

airplane moving towards the west with a speed of 482 km/hr
Speed or Velocity? Read the following and work with a partner to decide if the following represent “Speed” or “Velocity” airplane moving towards the west with a speed of 482 km/hr car moving at 80 km/hr Be ready to explain your answers

Speeding up and slowing down are changes in speed

Change in speed or direction
Acceleration Change in speed or direction An object is accelerating when it speeds up, slows down, or changes direction

Acceleration 3 Examples:
Case 1 – Interval increases because car is moving faster and faster Case 2 – Interval decreases because car is slowing down Case 3 – Interval stays the same, but direction of motion is constantly changing

Slowing down is sometimes called deceleration
Acceleration Slowing down is sometimes called deceleration TPS: work with a partner to explain why coming to a stop at a traffic light is acceleration. Be ready to share your answer

Newton’s First Law of Motion
Newton’s First Law of Motion states that an object will remain at rest, or move at a constant speed in a straight line, unless it is acted on by an unbalanced force

Newton’s First Law of Motion
inertia – tendency of an object to stay at rest or in motion Newton’s First Law of Motion is also called the Law of Inertia Watch this animation, then TPS to explain why is it important to wear seatbelts when riding in a car. Be prepared to share your thoughts with the class.

Newton’s First Law in action!
After watching the film clip, quickly sketch this drawing in your notebook. Add a seatbelt to the driver. Use another arrow to show the force that the seatbelt exerts to prevent the man from flying out of the car Newton’s First Law in action!

Now check your sketch by 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 Motion
Newton’s Second Law of Motion describes the relationship among force, mass, and acceleration Watch this clip and then TPS to explain what can cause the elephant to move faster.

Newton’s Second Law of Motion
Unbalanced forces cause objects to accelerate The amount by which an object accelerates depends on two things Size and direction of the force Mass of the object

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

Newton’s Second Law of Motion
If you apply the same amount of force to two objects with different masses, the object with the smaller mass will accelerate more than the object with the larger mass

TPS to discuss: How can you apply a force to two objects with different masses, but still have them accelerate at the same rate?

Newton’s Second Law of Motion
force = mass X acceleration F = m x a Force is measured in Newtons (N) Newton – unit of force equal to one kilogram-meter per second per second

Newton’s Third Law of Motion
Newton’s Third Law of Motion states that for every action force, there is an equal and opposite reaction force

Newton’s Third Law of Motion
Forces always act in pairs The two forces act in opposite directions

Newton’s Third Law of Motion
action force – force acting in one direction reaction force – force acting in the opposite direction (scroll down to boat animation) Watch the animation, then TPS to explain why the boat moved away from the dock.

Review Match the following to the Newton’s Law that explains the motion in each picture
1St Law ? 2nd Law? Or 3rd Law?