As shown in the figure, a paddle wheel is linked to a mass of 12 kg by fixed frictionless pulleys. The paddle is submerged in a liquid with a heat capacity of 4200 J K ⁻¹ , which is maintained inside an adiabatic container. Consider a time interval where the 12 kg block descends slowly through 70 cm . What is the amount of heat given to the liquid?

Step-by-step solution

The container is given to be adiabatic. By definition, an adiabatic process is one in which there is no heat transfer between the system and its surroundings. Therefore, the heat given to the liquid is Q = 0 J . The descending mass does mechanical work on the liquid ( W = mgh = 12 10 0.7 = 84 J ), which increases its internal energy, but the heat transferred remains zero.