Question

A 83 kg person escapes from a burning building by jumping from a window 21 m above a
catching net.
The acceleration of gravity is 9.81 m/s
2
.
Assuming that air resistance is simply a
constant 92 N force on the person during the
fall, determine the person’s velocity just before hitting the net.
Answer in units of m/s

Answer 1

Kinetic energy at net = (potential energy loss) - (work done against friction)

(1/2)M V^2 = M g H - 92*21

H = 21 m
M = 83 kg
g = 9.81 m/s^2

Solve for V.

Answer 2

27.8m/s2