Answer
The magnitude of the average force from the wall is $~~31,000~N$
Work Step by Step
We can find the bullet's initial kinetic energy:
$K = \frac{1}{2}mv^2$
$K = \frac{1}{2}(0.030~kg)(500~m/s)^2$
$K = 3750~J$
Since the bullet comes to a stop, the change in the mechanical energy is $~~-3750~J$
We can use the magnitude of the work done on the bullet by the wall to find the magnitude of the average force:
$F~d = 3750~J$
$F = \frac{3750~J}{d}$
$F = \frac{3750~J}{0.12~m}$
$F = 31,000~N$
The magnitude of the average force from the wall is $~~31,000~N$
