A 84-kg fireman slides down a 4-m pole by applying a frictional force of 416 N against the pole with his hands. If he slides from rest, how fast is he moving once he reaches the ground?

Answer 1

Fn = mg - Fk,
Fn=84*9.8 - 416 = 407.2 N.=Net force.

Fn = ma,
a = Fn/m = 407.2 / 84 = 4.85 m/s^2.

Vf^2 = Vo^2 + 2a*d,
Vf^2 = 0 + 9.7*4 = 38.78,
Vf = 6.23 m/s.