Find the time taken by a 500 W heater to raise the temperature of 50 kg of material of specific heat capacity 960 J kg^-1 K^-1, from 18°C to 38°C. Assume that all the heat energy supplied by heater is given to the material.

A fire truck uses 10,000 litres of water to extinguish a fire, cooling down the burning material from 500°C to 100°C. If the temperature of water increases by 40°C, how much heat energy is absorbed by it? (Specific heat capacity of water = 4200 J kg⁻¹ K⁻¹)

0.5 kg of lemon squash at 30°C is placed in a refrigerator which can remove heat at an average rate of 30 J s^-1. How long will it take to cool the lemon squash to 5°C ? Specific heat capacity of squash = 4200 J kg^-1 K^-1.

A mass of 50 g of a certain metal at 150°C is immersed in 100 g of water at 11°C. The final temperature is 20°C. Calculate the specific heat capacity of the metal. Assume that the specific heat capacity of water is 4.2 J g^-1 K^-1.