Net Force problem?

Question

If it takes a human cannonball 1.5 s to exit a 1.6 m long cannon, what is the average net force acting on the performer if his mass is 65 kg?

Answer 1

Assume zero initial velocity

d = v(0)*t + (1/2)(a)*t^2
1.6 = 0*t + .5at^2
3.2/(1.5^2) = a
a = 1.4 m/sec^2

Average Force = ma = 65 [kg] * 1.42 [m/s^2] = 92.4 N

Answer 2

u=0, t=1.5, s=1.6, a =a

s = ut + 0.5at^2

1.6 = 1.125a

a = 1.42ms^-2

F = ma = 65*1.42 = 92.4N