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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.
Solution
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
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