A student (m = 63 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a time of 0.0170 s. The average force exerted on him by the ground is +16500. N, where the upward direction is taken to be the positive direction. From what height did the student fall? Assume that the only force acting on him during the collision is that due to the ground.

.146 meters

186

To find the height from which the student fell, we can use the equations of motion in order to find the initial velocity, and then use the equation for free fall to find the height.

Step 1: Find the initial velocity (u) of the student.
We can use the equation of motion:

v = u + at

where:
v = final velocity (0 m/s, as the student comes to rest)
u = initial velocity (unknown)
a = acceleration (which is the average force exerted on the student divided by the mass of the student)
t = time taken to come to rest (0.0170 s)

Rearranging the equation, we have:

u = v - at

Substituting the values, we get:

u = 0 - (16500 N / 63 kg) * (0.0170 s)

Step 2: Calculate the height (h) using the equation for free fall:

h = (u^2) / (2g)

where:
h = height
u = initial velocity
g = acceleration due to gravity (which is approximately 9.8 m/s^2)

Substituting the values, we get:

h = (u^2) / (2 * 9.8 m/s^2)

Now substitute the value of u calculated in Step 1 to find the height.