### Multiple Choice

#### 3.1 Acceleration

Which variable represents displacement?

*a**d**t**v*

If a velocity increases from 0 to 20 m/s in 10 s, what is the average acceleration?

- 0.5 m/s
^{2} - 2 m/s
^{2} - 10 m/s
^{2} - 30 m/s
^{2}

#### 3.2 Representing Acceleration with Equations and Graphs

For the motion of a falling object, which graphs are straight lines?

- Acceleration versus time only
- Displacement versus time only
- Displacement versus time and acceleration versus time
- Velocity versus time and acceleration versus time

A bullet in a gun is accelerated from the firing chamber to the end of the barrel at an average rate of 6.30×10^{5} m/s^{2} for 8.10×10^{−4} s. What is the bullet’s final velocity when it leaves the barrel, commonly known as the muzzle velocity?

- 7.79 m/s
- 51.0 m/s
- 510 m/s
- 1020 m/s

### Short Answer

#### 3.1 Acceleration

True or False—The vector for a negative acceleration points in the opposite direction when compared to the vector for a positive acceleration.

- True
- False

- -5 m/s
- -1 m/s
- 1 m/s
- 5 m/s

How is the vector arrow representing an acceleration of magnitude 3 m/s^{2} different from the vector arrow representing a negative acceleration of magnitude 3 m/s^{2}?

- They point in the same direction.
- They are perpendicular, forming a 90° angle between each other.
- They point in opposite directions.
- They are perpendicular, forming a 270° angle between each other.

How long does it take to accelerate from 8.0 m/s to 20.0 m/s at a rate of acceleration of 3.0 m/s^{2}?

- 0.25 s
- 4.0 s
- 9.33 s
- 36 s

#### 3.2 Representing Acceleration with Equations and Graphs

If a plot of displacement versus time is linear, what can be said about the acceleration?

- Acceleration is 0.
- Acceleration is a non-zero constant.
- Acceleration is positive.
- Acceleration is negative.

True or False—The image shows a velocity vs. time graph for a jet car. If you take the slope at any point on the graph, the jet car’s acceleration will be 5.0 m/s^{2}.

- True
- False

When plotted on the blank plots, which answer choice would show the motion of an object that has uniformly accelerated from 2 m/s to 8 m/s in 3 s?

- The plot on the left shows a line from (0,2) to (3,8) while the plot on the right shows a line from (0,2) to (3,2).
- The plot on the left shows a line from (0,2) to (3,8) while the plot on the right shows a line from (0,3) to (3,3).
- The plot on the left shows a line from (0,8) to (3,2) while the plot on the right shows a line from (0,2) to (3,2).
- The plot on the left shows a line from (0,8) to (3,2) while the plot on the right shows a line from (0,3) to (3,3).

When is a plot of velocity versus time a straight line and when is it a curved line?

- It is a straight line when acceleration is changing and is a curved line when acceleration is constant.
- It is a straight line when acceleration is constant and is a curved line when acceleration is changing.
- It is a straight line when velocity is constant and is a curved line when velocity is changing.
- It is a straight line when velocity is changing and is a curved line when velocity is constant.

### Extended Response

#### 3.1 Acceleration

- The direction of the initial acceleration vector will point towards the wall and its magnitude will be less than the acceleration vector of the crash.
- The direction of the initial acceleration vector will point away from the wall and its magnitude will be less than the vector of the crash.
- The direction of the initial acceleration vector will point towards the wall and its magnitude will be more than the acceleration vector of the crash.
- The direction of the initial acceleration vector will point away from the wall and its magnitude will be more than the acceleration vector of the crash.

A car accelerates from rest at a stop sign at a rate of 3.0 m/s^{2} to a speed of 21.0 m/s, and then immediately begins to decelerate to a stop at the next stop sign at a rate of 4.0 m/s^{2}. How long did it take the car to travel from the first stop sign to the second stop sign? Show your work.

- 1.7 seconds
- 5.3 seconds
- 7.0 seconds
- 12 seconds

#### 3.2 Representing Acceleration with Equations and Graphs

True or False—Consider an object moving with constant acceleration. The plot of displacement versus time for such motion is a curved line while the plot of displacement versus time squared is a straight line.

- True
- False

- 0.574 s
- 0.956 s
- 1.53 s
- 1.91 s