NEET2026PhysicsThermodynamicsActual
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 :
Options
- A75 W
- B100 W
- C125 W
- D25 W
Correct answer
D. 25 W
Step-by-step solution
According to the first law of thermodynamics: dQ dt = dU dt + dW dt Given that the rate of heat supplied is dQ dt = 100 W and the rate of work done by the system is dW dt = 75 J/s = 75 W. Substituting the values: 100 = dU dt + 75 dU dt = 100 - 75 = 25 W The rate at which internal energy increases is 25 W. Answer: 25 W