The man jumps from the window of a burning hotel and lands i

The man jumps from the window of a burning hotel and lands in a safety net that stops him fall in 1.5 m. Determine the average force that the net exerts on the man if he enters the net at a speed of 30 m/s . Assume that the man\'s mass is 57 kg. Express your answer with the appropriate units.

Solution

Man stopped after moving d =1.5 meter distance

his velocity when he strikes the net was Vi = 30m/s

final velocity is Vf = 0

so retardation produced by net can be found by third equation of motion

Vf^2 = Vi^2 - 2*a*d

a = (Vf^2 - Vi^2) /2*d

a = 0-900 / 2*1.5

a = - 300m/s^2

so average force acting on the man

F = m*a

F = 57*300

F = 17100 Newton

net force is

Fnet = ma+mg

Fnet = 17100+57*9.8

Fnet = 17658.6 Newton