Name: _________________________ Period: __________ Due Date: __________ A

AP Physics 1 Homework - Segmented Motion

1. A ball is dropped from rest at the top of a tall building. The ball is in free-fall for the first 10 seconds of
its fall, and then afterward travels with constant velocity (called “reaching terminal velocity”) for an
additional 5 seconds. Assume that the acceleration of gravity is 10 m/s 2.

(a) Fill in the segmented motion diagram with given information. Then use logic and physics to fill in
the missing blanks. In the space below, write a narrative explaining how you found each value of v,
∆y, ∆t, and a (except for given values).

(b) Draw graphs of the downward distance y the ball traveled and the ball’s downward speed v as
functions of time. Note that the ball starts at y = 0 and down is positive.

(c) State the height of the building and explain how the height can be found from the velocity vs. time
graph.
.

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AP Physics 1 Homework - Segmented Motion A

2. A rocket initially at rest on the ground begins firing its engines at time t = 0. The rockets fire for 2
seconds, giving the rocket an upward acceleration of 30 m/s 2. The rocket engines then shut off and the
rocket then enters free-fall motion (use g = 10 m/s2).

(a) Fill in the segmented motion diagram with given information. Then use logic and physics to fill in
the missing blanks. In the space below, write a narrative explaining how you found each value of v,
∆y, ∆t, and a (except for given values). (Note the final velocity and final time and ∆t will be messy
numbers.)

(b) Draw graphs of the height y of the rocket and the rocket’s velocity v (where up is positive) as
functions of time.

(c) State the maximum height the rocket reaches and explain how this can be found from the velocity vs.
time graph.
.

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AP Physics 1 Homework - Segmented Motion A

3. A speeding motorist travels with a constant speed of 30 m/s on a straight road. At time t = 0, he passes a
hidden police car which is at rest. The instant that the motorist passes, the police car begins accelerating
at a constant rate of 4 m/s2 in order to catch the motorist.

(a) What quantity of motion do the motorist and police car both have equal to each other at the instant
the police car catches the motorist?

(b) Draw a graph of velocity vs. time for both the motorist and the police car. Label each one either
“motorist” or “police”. Both graphs should end at the time at which the police car catches the
motorist.

(c) In a narrative, fully explain the thought process that you used to construct the above graph. A
full-credit response would show understanding of important motion principles and would include
explicit statements of how much time it took for the police car to catch the motorist, how fast the
police car was moving upon reaching the motorist, and how far the police car had to travel to catch
the motorist.

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AP Physics 1 Homework - Segmented Motion A

4. The Texas Driver’s Handbook has a section dealing with making emergency stops. The handbook
indicates that, once it is clear that an emergency stop is required, it takes the average driver 1.5 seconds
to move their foot from the gas pedal to the brake pedal (this is called the “thinking time”). Once the
brake pedal is fully applied, the average car decelerates at a rate of 7 m/s 2 (during what is called the
“braking time”).

Suppose an average car moves with an initial speed of 30 mph (14 m/s). A child runs out into the street
ahead of the car. The driver takes time to react to the child’s presence in the roadway and then slams on
the brakes in order to stop.

(a) Draw a graph of the

(b) State the total time it took to stop the car and the total distance traveled by the car after the child ran
into the roadway. Explain how the graph was used to find these quantities.

(c) A student learning about emergency stops makes the following claim: “I bet that if the car was going
twice as fast, it would take twice as much time to stop the car, and the car would travel twice as far.”
Make a verbal argument that evaluates whether this claim is true, false, or partly true/partly false. As
part of your argument, make a new graph on the grid above and label this graph C. If the statement is
not fully true, conclude with a statement that is fully true, describing whether the stopping time
and/or distance are more than doubled or less than doubled.

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5. Points Given: (1) ___/10 (2) ___/10 (3) ___/10 (4) ___/10