Answer:
21420 J
Explanation:
Given that:
mass of the rider = 70 kg
the tension of the rope = 350 N
Using the concept of conservation of energy;
Work done = change in the Total energy ( ΔT.E)
where;
Work done (W) = ΔK.E + ΔP.E + ΔThermal Energy
Recall that the man proceeds with a constant speed, thus the change in K.E energy will be zero.
As such:
W = ΔP.E + ΔThermal Energy
We can now say that:
The thermal energy = W - ΔP.E
here;
W = force × displacement
The thermal energy = (350 × 120) - (70 × 9.8 × 30)
= 42000 - 20580
= 21420 J