A 100 kg block is started with a speed of 2.0 m s−1 on a long, rough belt kept fixed in a horizontal position. The coefficient of kinetic friction between the block and the belt is 0.20.
If the same experiment is carried out in vacuum inside an adiabatic chamber, the change in internal energy of the belt-block system will be -
0 J
The Kinetic energy which was last due to friction would have converted to heat. This heat would have been utilized to raise the of the only 2 bodies around i.e., the block temperature and the belt
Hence the macroscopic kinetic energy has been connected to heat which is then used to raise the internal energy (by raising the temperature) of the system. No energy leaves the system.