Afireman of mass 80 kg slides down a pole. when he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s. by how much has thermal energy increased during his slide?

3099 J

Explanation:

While the fireman  slides down, his initial gravitational potential energy is converted partially into kinetic energy, partially into thermal energy, so we can write:

(1)

where

where m=80 kg is the mass of the fireman, g=9.8 m/s^2 is the acceleration of gravity, is the change in height of the fireman.

The kinetic energy gained is

where v = 2.2 m/s is the speed reached by the fireman at the bottom of the slide

So now solving eq.(1) we find the increase in thermal energy :

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered