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Thermal Properties of Matter

JEE Main level, numerical answer, medium

57 of 126

Question 57 of 126

A water heater of power $2000W$ is used to heat water. The specific heat capacity of water is $4200J{kg}^{-1}{K}^{-1}$ . The efficiency of heater is $70%$ . Time required to heat $2kg$ of water from $10^{\circ}C$ to $60^{\circ}C$ is _____ $s$ .
(Assume that the specific heat capacity of water remains constant over the temperature range of the water).

Show answer and solution

Answer: 300

Heat provided to water will be responsible for increase in temperature. Therefore, we can write

\eta \times P\times t=M\times s\times \Delta T

Now,

\eta =\dfrac{70}{100}=0.7

and

\text{energy}=\text{power}\times \text{time}

.
Therefore,

t=\dfrac{2\times 4200\times \left(60^{\circ}-10^{\circ}\right)}{0.7\times 2000}s=300s

JEE Main question paper PDF

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JEE Main 2025 Apr 2 Shift 1 question paper

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