Question

A 190 g rock at 20°C is completely immersed in 600 g of water at 80°C. Which one of the following statements is true right after the rock goes in?

A. The water gives the rock thermal energy and gets no thermal energy in return.
B. The rock and the water give each other thermal energy, but the water gives more than it gets.
C. The rock gives the water thermal energy and gets no thermal energy in return.
D. It depends on the specific heat of the rock.
E. The rock and the water give each other thermal energy, but the rock gives more than it gets

Answer 1

Rock is completely immersed in hot water. By the second law of thermodynamics, thermal energy or heat is transferred from substance with higher temperature to substance with lower temperature until they come to thermal equilibrium i.e. both at same temperature.

It is given here that rock is at 20°C which is at lower temperature than water at 80°C. ∴Heat or thermal energy flows from water to rock. So, right choice is-

A. The water gives the rock thermal energy and gets no thermal energy in return.