JEE Main 2017 Physics question
A copper ball of mass 100 gm is at a temperature T. It is dropped in a copper calorimeter of mass 100 gm, filled with 170 gm of water at room temperature. Subsequently, the temperature of the system is found to be 75°C. T is given by- (Given : room temperature = 30°C, specific heat of copper = 0.1 cal/gm°C)
Answer: (B)
Solution
Heat lost = heat gained: 100 × 0.1 × (T − 75) = (100 × 0.1 + 170 × 1)(75 − 30) = 8100, so T − 75 = 810 and T = 885°C.