2. From the preceding calculation, it should be obvious that to experimentally time the
distance of fall for a dropped object is critical. To gain an appreciation of how the distance
of fall varies with time, consider the daring experimenter shown in GL Fig. 5.1. Jo-Jo
will illustrate the time-distance relationship of free fall by stepping off a high, vertical cliff
with a timer in one hand and a marker in the other. For each second of fall, he makes a
mark on the cliff face.
But wait. Jo-Jo wants you to determine how far he would fall during each second for
the first 5 seconds. He requests you plot the results on a distance versus time graph for a
visual display
Oh, one other thing. He wants to open his parachute when reaching 60 mi/h. At what
time, or between which seconds, should he do this?

The kinematics allows finding the relationships between the position, the velocity and the acceleration of the bodies, in this case the boy is in free fall down the cliff, as he has a stopwatch in his hand he can mark the position every second that he falls, taken the downward direction as positive.

y = y₀ + v₀ t + ½ g t²

Where y and y₀ are the current and initial height, v₀ the initial velocity, g the acceleration of gravity and t the time

As it is dropped, its initial velocity is zero and we place the zero of the reference system at the top of the cliff y₀ = 0

y = 0 + 0 + ½ g t²

y = ½ g t²

y = ½ 32.16 f²

y = 16.08 t²

Table 1 shows the distances for the first 5 seconds of the fall

t (s) y (ft)

0 0

1 16.08

2 64.32

3 144.72

4 257.28

5 402.0

In the attachment you can see a graph of distance versus time for this movement

b) We look for the time to obtain the speed of 60 mi / h

Let's reduce units of the speed to ft / s

v = 60 mi / h (5280 ft / 1 mi) (1h / 3600 s) = 88 ft / s

Let's use the kinematics relation

v = v₀ + g t

t = [tex]\frac{v -v_o}{g}[/tex]

t = [tex]\frac{88.0 - 0}{32.16}[/tex]

t = 2.7 s

Using the kinematics relations we were able to find the correct results

The distance traveled as a function of time

Tthe time for skull to open the paratroopers is 2.7 s

learn more about kinematics here:

https://brainly.com/question/5183024