1. 11.1 Distance and Displacement
Chapter 11 Motion
11.1 Distance and Displacement

2. Standards
SPS8a. Students will calculate velocity and acceleration

3. The earth is the most common frame of reference
Choosing a Frame of Reference
To describe motion accurately and completely, a frame of reference (a system of objects that are not moving with respect to one another) is necessary.
The earth is the most common frame of reference
If you are standing on the sidewalk, you see the cars driving past you. You and the cars are not moving with respect to one another. However, when you are in the car, you see the people on the sidewalk you are passing by, but when you look at the other people inside the car, they do not seem to be moving at all because you are moving with one another. Therefore, the people inside the car with you are not a frame of reference of motion.

4. Motion – a change in position in a certain amount of time
Reference point
Motion

5. Distance is the length of the path between two points.
The SI unit is the meter (m).
Large distances are commonly measured in kilometers (km).
Distances less than a meter are measured in centimeters (cm).

6. Distance vs. Displacement
Displacement is the direction from the starting point AND the length of a straight line from the starting point to the ending point.
Example: 5 blocks North

7. A vector is a quantity that has magnitude and direction.

8. Displacement Along a Straight Line
Combining Displacements
Displacement Along a Straight Line
When two displacements, represented by two vectors, have the same direction, you can add their magnitudes.
If two displacements are in opposite directions, the magnitudes subtract from each other.

9. Displacement That Isn’t Along a Straight Path
Combining Displacements
Displacement That Isn’t Along a Straight Path
When two or more displacement vectors have different directions, they may be combined by graphing.

10. Displacement That Isn’t Along a Straight Path
Following this path, the boy walked a total of 7 blocks
The red line shows the resultant vector, the sum of two or more vectors. In this case it shows the displacement

11. standing at the side of the road
Review
A car is driving down the highway. From which frame of reference does it appear to not be moving?
standing at the side of the road
a car driving at the same speed but going the opposite direction
sitting inside the car
an airplane flying overhead

12. c. sitting inside the car
Review
A car is driving down the highway. From which frame of reference does it appear to not be moving?
c. sitting inside the car

13. meter. centimeter. kilometer. mile.
Review
The SI unit of distance that would be most appropriate for measuring the distance between two cities is the
meter.
centimeter.
kilometer.
mile.

14. Review
The SI unit of distance that would be most appropriate for measuring the distance between two cities is the
c. kilometer.

15. If you walk across town, taking many turns, your displacement is the
Review
If you walk across town, taking many turns, your displacement is the
total distance that you traveled.
distance and direction of a straight line from your starting point to your ending point.
distance in a straight line from your starting point to your ending point.
direction from your starting point to your ending point.

16. If you walk across town, taking many turns, your displacement is the
Review
If you walk across town, taking many turns, your displacement is the
b. distance and direction of a straight line from your starting point to your ending point.

17. Review
You travel 30 km west of your home and then turn around and start going back home. After traveling 10 km, what is your displacement from your home?
20 km
20 km west
40 km
40 km west

18. Review
You travel 30 km west of your home and then turn around and start going back home. After traveling 10 km, what is your displacement from your home?
b. 20 km west