A 70.0-kg man jumps 1.00 m down onto a concrete walkway.His downward motion stops in 0.0200 seconds.If he forgets to bend his knees,what force is transmitted to his leg bones?

Question

Quizplus · Accepted Answer

We can use the formula:

force = mass x acceleration

The acceleration is given by:

acceleration = (final velocity - initial velocity) / time

Since the man's downward motion stops, the final velocity is zero. The initial velocity can be calculated from the height of the jump:

initial velocity = sqrt(2 x g x height)

where g is the acceleration due to gravity (9.81 m/s^2).

Substituting the given values, we get:

initial velocity = sqrt(2 x 9.81 x 1.00) = 4.43 m/s

The acceleration is:

acceleration = (0 - 4.43) / 0.0200 = -221 m/s^2

Note that the acceleration is negative, indicating that it is in the opposite direction to the motion.

Finally, we can calculate the force:

force = 70.0 x (-221) = -15,470 N

The negative sign indicates that the force is acting in the opposite direction to the man's motion. Taking the absolute value, we get:

force = 15,470 N

which is closest to choice A, 15,500 N.

A 700-Kg Man Jumps 1