Answer:
1000 J of thermal energy is generated.
Explanation:
The attached figure shows the whole scenario. It consists of three types of energies i.e. Gravitational Potential Energy, Kinetic Energy and thermal energy.
We know that the energy of a system remains conserved. In this case, the gravitational potential energy is the sum of kinetic energy and the thermal energy.
GPE = KE +TE
8000 J = 7000 J + TE
TE = 1000 J
So, the thermal energy is 1000 J. Hence, this is the required solution.
