1. Chapter 11 Motion

2. Chapter 11
FRAME OF REFERENCE

3. http://www. visualnews
Who is upside-down?

4.
Who is upside-down?

5. Motion Motion is a change in location (you’re moving) Relative Motion:
Right now you are all sitting still.
Are you still moving?
Can you ever stop moving?

6. Motion Motion is Relative:
Relative to the Sun you are traveling 100,000 km/hr (62,137 mph)

7. Motion is Relative
You are sitting on a bus with a pencil over your head, traveling at 50 miles per hour
Relative to the bus, what is the pencil’s speed?
Relative to the road, what is the pencil’s speed?
Drop the pencil.
Relative to the road what is the speed of the pencil?
This means the pencil will land (behind you, in front of you, behind you)?

8. Distance/Displacement
Distance: measurement of length between two points (no direction)
Since it has no direction it’s a scalar quantity
How far it’s traveled
Displacement: change in original position (direction)
Since it has direction it’s a vector quantity
A vector has both direction and magnitude (size)

9. Distance/Displacement Example
0 Miles
50 Miles
30 Miles
South
Distance: Car traveled 50 miles, then backed up 30 miles
50mi + 30mi = 80 miles
Displacement: Car traveled 50 miles, then backed up 30 miles
30mi (from original position)

10. Distance/Displacement Example
Distance: Runner runs around the 400m track.
Displacement: 0m because he’s right were he started

11. Distance/Displacement Example

12. Speed/Velocity Speed is how fast an object is moving Velocity
It is a scalar quantity
Since it’s a scalar quantity it has only magnitude (size)
Units are m/s
Velocity
It is a vector quantity
It has magnitude (size) and direction
If either the speed or the direction changes, the velocity changes

13. Average Speed/ Instantaneous Speed
Instantaneous Speed: is the speed at any given second (when you check your speedometer)
Average Speed: is the calculation of Distance/Time

14. Acceleration
Acceleration is a vector quantity (magnitude/direction) that is defined as the rate of which an object changes it’s speed.
An object is accelerating if it’s speed or direction is changing
Units are m/s2
To calculate acceleration:
A= change in velocity
time

15. Acceleration On a circular track a car is keeping constant speed, but
the velocity is always changing. Why?