### Short Answer

## 2.1 Relative Motion, Distance, and Displacement

While standing on a sidewalk facing the road, you see a bicyclist passing by toward your right. In the reference frame of the bicyclist, in which direction are you moving?

- in the same direction of motion as the bicyclist
- in the direction opposite the motion of the bicyclist
- stationary with respect to the bicyclist
- in the direction of velocity of the bicyclist

## 2.2 Speed and Velocity

What can you infer from the statement, *Velocity of an object is zero*?

- Object is in linear motion with constant velocity.
- Object is moving at a constant speed.
- Object is either at rest or it returns to the initial point.
- Object is moving in a straight line without changing its direction.

## 2.3 Position vs. Time Graphs

A hockey puck is shot down the arena in a straight line. Assume it does not slow until it is stopped by an opposing player who sends it back in the direction it came. The players are 20 m apart and it takes 1 s for the puck to go there and back. Which of the following describes the graph of the displacement over time? Consider the initial direction of the puck to be positive.

- The graph is an upward opening V.
- The graph is a downward opening V.
- The graph is an upward opening U.
- The graph is downward opening U.

A defensive player kicks a soccer ball 20 m back to her own goalie. It stops just as it reaches her. She sends it back to the player. Without knowing the time it takes, draw a rough sketch of the displacement over time. Does this graph look similar to the graph of the hockey puck from the previous question?

- Yes, the graph is similar to the graph of the hockey puck.
- No, the graph is not similar to the graph of the hockey puck.
- The graphs cannot be compared without knowing the time the soccer ball was rolling.

What are the net displacement, total distance traveled, and total average velocity in the previous two problems?

- net displacement = 0 m, total distance = 20 m, total average velocity = 20 m/s
- net displacement = 0 m, total distance = 40 m, total average velocity = 20 m/s
- net displacement = 0 m, total distance = 20 m, total average velocity = 0 m/s
- net displacement = 0 m, total distance = 40 m, total average velocity = 0 m/s

## 2.4 Velocity vs. Time Graphs

What would the velocity vs. time graph of the object whose position is shown in the graph look like?

- It is a straight line with negative slope.
- It is a straight line with positive slope.
- It is a horizontal line at some negative value.
- It is a horizontal line at some positive value.

Which statement correctly describes the object’s speed, as well as what a graph of acceleration vs. time would look like?

- The object is not speeding up, and the acceleration vs. time graph is a horizontal line at some negative value.
- The object is not speeding up, and the acceleration vs. time graph is a horizontal line at some positive value.
- The object is speeding up, and the acceleration vs. time graph is a horizontal line at some negative value.
- The object is speeding up, and the acceleration vs. time graph is a horizontal line at some positive value.

Calculate that object’s net displacement over the time shown.

- 540 m
- 2,520 m
- 2,790 m
- 5,040 m

What is the object’s average velocity?

- 18 m/s
- 84 m/s
- 93 m/s
- 168 m/s