Extended Response

3.1 Acceleration

29 .

A test car carrying a crash test dummy accelerates from

0

30\,\text{m/s}

and then crashes into a brick wall. Describe the direction of the initial acceleration vector and compare the initial acceleration vector’s magnitude with respect to the acceleration magnitude at the moment of the crash.

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.

30.

A car accelerates from rest at a stop sign at a rate of 3.0 m/s² 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/s². 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

31.

True or False: Consider an object that starts from rest and moves 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

32 .

You throw a ball straight up with an initial velocity of 15.0 m/s. It passes a tree branch on the way up at a height of 7.00 m. How much additional time will pass before the ball passes the tree branch on the way back down?

0.574 s
0.956 s
1.53 s
1.91 s