Question

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^-1K^-1, from 18°C to 38° C. Assume that all the heat energy supplied by the heater is given to the material.

Answer 1

Power of heater (P) = 500 W

mass of material (m) = 50 kg

Specific heat capacity of material c = 960 J kg^-1K^-1

Change in temperature ΔT = (38 − 18)°C = 20°C (or 20 K)

ΔQ = mcΔT

ΔQ = 50 × 960 × 20

Time taken by a heater to raise the temperature of material

`"t" = (Δ"Q")/ "P" `

`"t" = (50 xx 960 xx 20)/ 500`

t = 1920 seconds 

t = 32 min