Respuesta :
F = (mass)(acceleration) = ma
m = 0.2 kg
Vi = 32 m/s
t = 0.5 s
Vf = 0 m/s (since it was put to stop)
a=(Vf-Vi)/t
a=(0-32)/0.5
a = 64 m/s^2 (decelerating)
F = ma = (0.2 kg)(64 m/s^2)
F = 12.8 N
Hope this answer will be a good help for you.