1. Chapter 10
Motion & Momentum

2. Ch 10.1 – What is Motion? All matter is constantly in motion
Motion involves change in position
1. An object
changes position
relative to a
reference point

4. 2. Distance – the total length of the route an object travels when it moves

5. 3. Displacement – includes the distance and direction of the stopping point from the starting point

6. C. Speed – distance traveled divided by the time taken to travel that distance 1. Formula for speed: speed = distance/time 2. SI Unit for speed: meters per second (m/s)

7. Calculating Speed
Calculate the speed of a swimmer who swims 100m in 56s
Speed = distance / time or
D = 100m
T = 56s
Speed = 100m = 1.8 m/s
56s
More practice problems p.284

8. 3. An object in motion can change speeds many times as it moves from one point to another, speeding up or slowing down a) Average speed – the total distance traveled divided by total time taken

9. b) Instantaneous speed – an object’s speed at a particular moment in time c) Constant speed – occurs when an object travels at a steady rate with the same instantaneous speed for some period of time

10. D. Graphing Motion 1. Motion can be graphed on a distance-time graph a) Distance is plotted on the vertical axis b) Time is plotted on the horizontal axis

12. 2. The steeper the line the faster the speed

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14. 3. A horizontal line indicates that no change in position is occurring and the speed is zero

16. E. Velocity – the speed of an object AND its direction of motion 1
E. Velocity – the speed of an object AND its direction of motion 1. Velocity changes if either or both of these factors is altered

17. Ch Acceleration
Acceleration – change in velocity divided by the time for the change to occur
1. Can include an
object speeding up,
slowing down,
and/or changing
direction

18. 1. Formula for acceleration:
B. Acceleration can be calculated if you know how an object’s velocity has changed during a given time period
1. Formula for acceleration:
Acceleration = final speed – initial speed
time
a = (Sf – Si) / t

19. a) SI Unit for acceleration: meters per second squared (m/s2) b) Acceleration number will be positive when an object is speeding up and negative when slowing down

20. Calculating Acceleration
Calculate the acceleration of a bus whose speed changes from 6m/s to 12m/s over a period of 3s
A = (final speed – initial speed)
time
A = 12 m/s – 6 m/s = 6 m/s = 2 m = 2 m/s2
3 s s s x s
More practice problems p.290

21. C. Graphing Acceleration 1
C. Graphing Acceleration 1. Acceleration can be graphed with a speed – time graph a) Speed is plotted on the vertical axis b) Time is plotted on the horizontal axis

22. 2. An object that is speeding up will have a line that slopes upward 3
2. An object that is speeding up will have a line that slopes upward 3. An object that is slowing down will have a line that slopes downward 4. An object moving at a constant speed will have an acceleration of zero, and a horizontal line on the graph

23. Speed – Time Graph AKA… (speed) (constant speed) Positive Acceleration
Negative Acceleration

24. Ch 10.3 - Momentum The amount of matter that an object has is its mass
1. Inertia – the tendency of an object to resist change in motion; directly correlates to its mass

25. B. Momentum – measure of how hard it is to stop an object 1
B. Momentum – measure of how hard it is to stop an object 1. Calculated as mass times velocity 2. Formula for momentum: momentum = mass x velocity (p = mv)

26. Calculating Momentum
Calculate the momentum of a 14-kg bicycle traveling north at 2 m/s
P = mv
P = 14 kg x 2 m/s north
P = 28 kg x m/s north

27. 3. Momentum increases if the mass or velocity of the object increases

28. Which has more Momentum?

29. 4. Momentum has direction that is the same direction as its velocity
ex: P = 28 kg x m/s north

30. C. Law of Conservation of Momentum 1
C. Law of Conservation of Momentum 1. The total momentum of objects that collide with each other does not change

31. 2. There are many ways collisions can occur a) Objects may stick together and move still stuck together b) Objects may bounce off each other and transfer momentum from one to the other

33. 3. In all cases, the total momentum of the objects that collide is the same before and after the collision