Answer:
-355 N
Explanation:
We can solve this problem using impulse. Impulse (J) is equal to the average force (F) times the change in time (Δt). It is also equal to the change in momentum (Δp). Momentum (p) is equal to the mass (m) times the velocity (v). Since mass is constant, the change in momentum is equal to the mass times the change in velocity.
J = J
FΔt = Δp
FΔt = mΔv
F (1.2 s) = (71 kg) (4.0 m/s − 10.0 m/s)
F = -355 N