During a circus performance, a 71.2-kg human cannonball is shot out of an 18.0-m-long cannon. If the human cannonball spends 0.785 s in the cannon, determine the average net force exerted on him in the barrel of the cannon. (Assume the acceleration is constant.)

F=ma = 71.2 * 58.42 = 4159.5 N

Explanation:

for FORCE we need a: acceleration (F=ma)

for acceleration we can apply the second equation of motion

s = ut + 0.5at^2

where

s = 18 m ( displacement)

u = 0 m/s (initial velocity)

t = 0.785 s (time)

18 = 0.5 * a * (0.785)^2

a = 58.42 m/s^2

now

F=ma = 71.2 * 58.42 = 4159.5 N

see earlier answer