Q = ? m = 135 L = 135 kg c = 4200 J kg-1 K-1 ΔT = 70 – 20 = 50 K Q = mcΔT = 135 x 4200 x 50 = 28 350 000 J= 28 MJ

A hot water tank contains 135 L of water. Initially the water is at 20 ˚C. Calculate the amount of energy that must be transferred to the water to raise the temperature to 70˚C.