Properties Of Solids And Liquids Question 109

Question: Water of volume 2 litre in a container is heated with a coil of 1kW at 27C . The lid of the container is open and energy dissipates at rate of 160J/s. In how much time temperature will rise from 27C to 77C [Given specific heat of water is 4.2kJ/kg ] [IIT-JEE (Screening) 2004]

Options:

A) 8 min 20 s

B) 6 min 2 s

C) 7 min

D) 14 min

Show Answer

Answer:

Correct Answer: A

Solution:

Heat gained by the water = (Heat supplied by the coil) - (Heat dissipated to environment)

therefore mc Δθ=PCoil tPLoss t

therefore 2×4.2×103×(7727)=1000t160 t

therefore t=4.2×105840=500 sec =8 min 20 sec



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