A military parachutist fell 0.37km from...

Question

During World War 2, a military parachutist fell 0.37km from an airplane without being able to open his chute, but luckily was able to land in snow, suffering only with minor injuries. Assume that his speed at impact was 56 m/s, and his mass, including his gear was 85kg, and that the magnitude of force on him from the snow was at the survivable limit of 1.2 x 10^5 N. What is the magnitude of the impulse on him from the snow?

Answer 1

To solve the problem, we will use Newton's second law in a form that was presented by Newton in his famous "Principia" : The impulse of force acting on a body is equal to the change in its linear momentum:

F·Δt = Δ(mv).

From here the impulse of force is equal to

I = mΔv

Velocity is changing from v = 56 m/s to 0.

Finally we get

I = 85 kg ·56 m/s = 4 760 N·s = 4.8 kN·s