Question

If you slide down a rope, it's possible to create enough thermal energy to burn your hands or your legs where they grip the rope. Suppose a 40 kg child slides down a rope at a playground, descending 1.5 m at a constant speed. How much thermal energy is created as she slides down the rope? Assume that all potential energy can be transformed into thermal energy.

Answer 1

Answer:

588J

Explanation:

Descending at constant speed means that the kinetic energy remained constant, so the potential energy lost was mostly transformed into thermal energy (we will assume all of it). The difference on potential energy is:

$\Delta U=U_f-U_i=mgh_f-mgh_i=mg(h_f-h_i)=(40kg)(9.8m/s^2)(-1.5m)=-588J$

So this potential energy lost is the thermal energy gained.