Power of heater P = 600 W
Mass of liquid m = 4.0 kg
Change in temperature of liquid = (15 − 10)oC = 5oC(or 5 K)
Time taken to raise its temperature = 100s
Heat energy required to heat the liquid
ΔQ = mcΔT
And
ΔQ = P × t = 600 × 100 = 60000J
c = ΔQ/mΔT = 60000/4 x 5 = 3000 Jkg-1K-1
Heat capacity = c × m
Heat capacity = 4 × 3000 = 1.2 × 104 J/K