1. Most of the changes you observe are the result of matter in motion.
What is Motion?
Most of the changes you observe are the result of matter in motion.

2. Motion
Motion occurs when an object changes its position over a period of time
Are you moving right now?
YES!
The Earth’s orbit around the sun is 600 million miles,
We are traveling at 66,000 mi/hr through space!
We are rotating at a rate of approximately mi/hr

3. It’s all Relative!
Motion can only be detected when one object can be compared with another
We don’t feel like we are moving because we are moving with the Earth.
However, in the car we feel like we are moving fast because of the stationary objects along the side of the road

4. Speed The rate of change of motion Average speed = distance/time
The units are therefore m/s

5. D S T The Speed Triangle D equals distance S equals average speed
T equals time

6. Practice Questions: 40.0 km/hr 333.3 km/hr 75.0 mi. 27.3 hr
A car travels 120 km in 3 hours. What is its speed?
A train travels 500 km in 1.5 hours. What is its speed?
If a car was moving at 25 mi/hr and it took you 3 hours to get to your destination, then how far did you travel?
You are planning a trip. Your destination is 1,500 miles away. You plan to drive 55 miles per hour. How long will it take to arrive at your destination?
40.0 km/hr
333.3 km/hr
75.0 mi.
27.3 hr

7. Speed Changes at Constant Rates
Time

8. Constant Speed
Speed
Time

9. Speed Changes at Various Rates
Time

10. DO NOW
If I need to be at an appointment at 2:00 and I have to travel 10 miles. Will I make it if I walk at a speed of 5 miles per hour and it is now 1:00?
T= D/s
= 10/5
=2 hours
NO, your late

11. Displacement Measures the change in position of an object
Only the starting and ending points are used to find displacement
Direction of motion is important A B

12. Velocity The rate of change of displacement
Includes both speed and direction
Average velocity = displacement over time
Average speed is not always the same as average velocity

13. D V T The Velocity Triangle D equals displacement
V equals average velocity V T
T equals time

14. Speed versus Velocity If this runner completes her
1 km run in 0.1 hours,
her average speed is
1km/0.1hr or 10km/hr
However, since she ended up where she started,
her total displacement is zero,
her average velocity is
0km/ 0.1hr or 0km/hr

15. Relative Motion Relative to a frame of reference Five steps backward
Three steps forward
Total displacement is -2, or two steps behind where you began.

16. Relative Velocity
A train is moving 20 km/h north relative to the ground.
If you are on the sidewalk, the train appears to be moving at 20 km/h north.
If you are riding in a car going 15 km/h north, the train appears to be moving more slowly, 5 km/h north.
If you are riding in a car going 15 km/h south, the train appears to zip by at 35 km/h.
Only your frame of reference changes!

17. Acceleration Rate of change of velocity
How is velocity changing over time
A = Vf- Vi t
Change in velocity
Over time.
UNITS:
Distance/time/time
m/s2
mph/s
km/h/s

18. DO NOW What is the difference between speed and velocity?
Velocity includes DIRECTION!
Do speed and velocity have to be the same?
NO!
If I walk to my mailbox and back what was my displacement? 0!

19. What does it mean if acceleration is negative?
Acceleration is positive if velocity is increasing
Acceleration is negative if velocity is decreasing
Acceleration is zero if there is no change in velocity

20. Constant Speed 10 m/s Average Speed = 50 40 Distance (m) 30 20 10 5 11 2 3 4
Time (sec)

21. Reading a distance vs time graph
The slope of the line determines speed.
The _________ slope the _________
the speed.
The _________ slope the ________
the speed

22. DO NOW What is the formula for Speed/velocity? S = d/t
What is needed for velocity?
Direction!
What is the formula for acceleration?
A= Vf-Vi t

23. Varying Speed 10 m/s Average Speed = 50 40 Distance (m) 30 20 10 5 1 21 2 3 4
Time (sec)

24. Graphing Acceleration
Time (sec)
Distance (m)

25. Constant Speed
Varying speed
Speed
Speed
Time
Time
Constant Speed
Acceleration
Distance
Distance
Time
Time

26. Acceleration Due to Gravity

27. An attractive force between objects of mass
What is Gravity
An attractive force between objects of mass
Galileo Galilei
Sir Issac Newton
Albert Einstein

28. The acceleration at the earth’s surface is a constant 9
The acceleration at the earth’s surface is a constant 9.80 m/s2 toward the center of the Earth.

29. Acceleration Due to Gravity “g”
“g” - A constant acceleration due to the attractive force of gravity between an object and the Earth

30. Inertia and Momentum
As we already know, mass is the amount of matter an object possesses
Inertia is the measure of an object’s tendency to remain at rest or stay in constant motion
Momentum is the quantity of motion for an object

31. Momentum
Thanks to Sir Isacc Newton, we can describe momentum as the product of mass and velocity
Momentum = mass x velocity
p = mv
where p is the symbol for momentum
Momentum is additive

32. Examples +3 kg m/s -2 kg m/s p = +1 kg m/s +3kg m/s -3kg m/s

33. Conservation of Momentum
This law states that the momentum of a system of objects will not change unless an outside force acts on the group.
0 kg m/s
0.2 kg m/s
Before Collision
Ptotal= 0.2 kg m/s
0.15 kg m/s
0.05 kg m/s
After Collision
Ptotal= 0.2 kg m/s