NEET 2026, Physics Q16: Laws of Thermodynamics

NEET2026Physics

An electric heater supplies heat to a system at a rate of 100 W. If the system performs work at a rate of 75 J/s, then the rate at which internal energy increases will be :

A
75 W
B
25 W
C
100 W
D
125 W

Solution

By the first law of thermodynamics:

$\frac{d Q}{d t} = \frac{d U}{d t} + \frac{d W}{d t}$

$100 = \frac{d U}{d t} + 75$

$\frac{d U}{d t} = 25$ W.

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NEET 2026, Physics Q16: Laws of Thermodynamics

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