Physics

### 3.1Acceleration

21.

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

1. True
2. False
22.
If a car decelerates from $20 m slash s$ to $15 m slash s$ in $5 s$, what is $normal upper Delta v$?
1. -5 m/s
2. -1 m/s
3. 1 m/s
4. 5 m/s
23.

How is the vector arrow representing an acceleration of magnitude 3 m/s2 different from the vector arrow representing a negative acceleration of magnitude 3 m/s2?

1. They point in the same direction.
2. They are perpendicular, forming a 90° angle between each other.
3. They point in opposite directions.
4. They are perpendicular, forming a 270° angle between each other.
24.

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/s2?

1. 0.25 s
2. 4.0 s
3. 9.33 s
4. 36 s

### 3.2Representing Acceleration with Equations and Graphs

25.

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

1. Acceleration is 0.
2. Acceleration is a non-zero constant.
3. Acceleration is positive.
4. Acceleration is negative.
26.

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/s2.

1. True
2. False
27.

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?

1. 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).
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).
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).
4. 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).
28.

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

1. It is a straight line when acceleration is changing and is a curved line when acceleration is constant.
2. It is a straight line when acceleration is constant and is a curved line when acceleration is changing.
3. It is a straight line when velocity is constant and is a curved line when velocity is changing.
4. It is a straight line when velocity is changing and is a curved line when velocity is constant.