JEE Main 2014PhysicsThermal Properties of MatterMediumMCQ

JEE Main 2014 — Thermal Properties of Matter Question with Solution

JEE Main 2014 (09 Apr Online)

Question

Water of volume 2 L in a closed container is heated with a coil of 1 kW. While water is heated, the container loses energy at a rate of 160 J/s. In how much time will the temperature of water rise from 27oC to 77oC ? (Specific heat of water is 4.2 kJ/kg and that of the container is negligible).

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Show full solutionCorrect option: A
Correct answer
A8 min 20 s

Step-by-step explanation

P = 1 0 0 0  watt

∴   Pin=1000-160 J/s=840 J/s

Now,   d Q dt = ms dT dt

∴    840=msdTdt

∴    dt = ms 8 4 0 dT

Integrating both sides we have;

t = ms 8 4 0 ∫ dT

    = 2 × 1 0 0 0 × 1 0 - 6 × 1 0 0 0 × 4.2 × 1 0 0 0 8 4 0 × 5 0

    = 5 0 0 sec

    = 8  min 2 0 sec

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About this question

This is a previous-year question from JEE Main 2014, covering the Thermal Properties of Matter chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.