Motion - an object’s relative to a point over a period of time

1. change in position DESCRIBING MOTION Motion - an object’s relative to a point over a period of time Reference Point – an that appears to stay in Motion is ____________ to a reference point that is ______________ for the situation reference object place relative relevant

2. Click me to see the two horses standing side by side. Click me to see the two horses after one has moved. EXAMPLE 1:Two horses are standing side by side. One of them moves. How can you tell which one has moved?

3. Click me to see the two horses standing side by side. Click me to see the two horses after one has moved. EXAMPLE 2:Two horses are standing side by side. One of them moves. How can you tell which one has moved? Buildings, trees, and mountains are all useful reference points.

4. DISTANCE far Distance – how it is from point to point in any ; the total of the path traveled starting stopping direction length End Follow all the loops Start

5. DISPLACEMENT Displacement - measures the and between theposition and the position Think: “As the bird flies” – straight line path in ONE direction. distance direction starting ending Start End

6. DISTANCE & DISPLACEMENT DISTANCE DISPLACEMENT

7. A Distance D Displacement B C

8. total distance total time Average speed = SPEED distance Speed – the traveled divided by the amount of EXAMPLE: A dog ran 25 miles in 5 hours. His speed is 5 miles per hour. (25 miles ÷ 5 hours) time

9. MOTION GRAPHS graph • Motion can be plotted on a _________ with time on the horizontal axis and distance on the vertical axis. This distance-time graph shows how the distance traveled by a sprinter changed during a 100-m race.

10. total distance total time Average speed = 100 m 12 seconds Avg. Sp. = In the graph below, what was the sprinter’s average speed over the entire race? Avg. Sp. = 8.33 m/s

11. Here’s a Riddle: Two birds leave the same tree at the same time. They both fly at 10 km/h for 1 hour, 15 km/h for 30 minutes, and 5 km/h for 1 hour. But they don’t end up at the same place. Why not? The birds were flying in different directions! Their speed was the same, but the direction they flew was different. So, their VELOCITIES differed.

12. VELOCITY speed Velocity – the measure of in a particular EXAMPLE: 5 miles per hour west direction

13. ACCELERATION change • Acceleration – the in velocity divided by the amount of over which the change occurs • Acceleration can take place when an object changes , • , or both. time direction speed

14. FORCE push pull Force – a or a that has size and direction The motion of an object when a force acts on it. Force makes objects speed up, slow down, or change direction. Force causes acceleration. changes

15. INERTIA Inertia – measures an object’s tendency to changing its and depends on the amount of an object has. motion resist mass

16. INERTIA EXAMPLE 1 The more mass an object has, the its inertia. greater An elephant has more inertia than a mouse because the elephant has more mass

17. INERTIA EXAMPLE 2 The more inertia an object has, the effect a force has on its motion. less If you kick an empty box and a full box with the same amount of force, the full box will not move as far.

18. INERTIA EXAMPLE 3 The more inertia an object has, the harder it is to start the object moving or slow it down. Is it easier to push a Volkswagen Beetle or an 18-Wheeler Truck?

19. BALANCED FORCES cancel Balanced Forces – forces that each other out because they are and acting in directions. The object’s motion does not change. equal opposite The object won’t move. Both forces pushing on the box are opposite and equal. 5N 5N

20. UNBALANCED FORCES NOT Unbalanced Forces – do cancel each other out. An object’s motion will if unbalanced forces act on it. _______ force is the difference between two forces. change Net

21. Net Force Example 15N 5N 15 Newtons of force to the right 5 Newtons of force to the left Net Force = 10 Newtons with motion to the right

22. 1000 Newtons 500 Newtons UNBALANCED FORCES The forces shown above are PUSHING / PULLING forces .

23. 1000 Newtons 500 Newtons UNBALANCED FORCES The forces shown above are WORKING TOGETHER / OPPOSITE FORCES.

24. 1000 Newtons 500 Newtons UNBALANCED FORCES The forces are EQUAL / NOT EQUAL.

25. 1000 Newtons 500 Newtons UNBALANCED FORCES The forces DO / DO NOT balance each other.

26. 1000 Newtons 500 Newtons UNBALANCED FORCES The net force is 500N TO THE RIGHT / 500N TO THE LEFT / ZERO.

27. 1000 Newtons 500 Newtons UNBALANCED FORCES There IS / IS NO motion.

28. FRICTION force Friction – a that exists between two surfaces Friction is present in almost all motion. Friction occurs between any two surfaces that slide past each other. touching

29. FRICTION Friction between the tire and the ground helps the wheels on this car turn without slipping.

30. FRICTION Air Resistance ______________________ is the pushing of air against the surface of an object. EXAMPLE: You feel air resistance when you place your hand in the air rushing past a moving car.

31. GRAVITY force Gravity – the that all objects with exert on other matter. Gravity is affected by: ______________ - amount of matter in an object ______________- how far away an object is mass Mass Distance

32. If you weigh 100 pounds here on Earth… …then your weight on the Moon would be 17 pounds! GRAVITY Weight __________- the measure of the gravitational force between an object and the planet or moon where the object is.