work power and forces

Question

dan is landing from a jump. His mass is 65kg, and he lands from the jump with a downward velocity of 4 m/s at contact.

a) what impulse is needed to bring him to a stop as he is landing?

b) if the contact time during landing was 0.19s, how much net force would be applied to him during the landing?

Answer 1

(a) Impulse is defined as F_net x Δt = m x Δv, where Δt and Δv are the time and velocity changes during impact. As the velocity goes from 4 m/s to zero, and the mass is 65 kg, the impulse is 260 kgm/s.

(b) To get the net force, use F_net = mΔv / Δt = 260 kgm/s / 0.19 s = 1368 Newtons.