NUST NET Engineering Test Physics: Heat & Thermodynamics MCQs

Practice Heat & Thermodynamics MCQs for NUST NET Engineering Test Physics — topic-wise sets with solved answers.

NUST NET Engineering Test Physics: Heat & Thermodynamics MCQs — sample questions

  1. Question 1

    Q1. For an ideal gas, the internal energy is a function of

    • A) temperature only
    • B) pressure only
    • C) volume only
    • D) both temperature and pressure

    Answer: temperature only

    Explanation: Internal energy (U) of an ideal gas depends only on temperature, as per the ideal gas model, U = f(T) only.

  2. Question 2

    Q2. The efficiency of a Carnot engine is 50%. The temperature of the sink is 27°C. The temperature of the source is

    • A) 327°C
    • B) 127°C
    • C) 227°C
    • D) 300°C

    Answer: 327°C

    Explanation: Efficiency = 1 - (T_sink / T_source). Given efficiency = 0.5, T_sink = 300K, we can solve for T_source = 600K or 327°C.

  3. Question 3

    Q3. The root mean square speed of gas molecules is directly proportional to

    • A) √T
    • B) √P
    • C) T
    • D) P

    Answer: √T

    Explanation: v_rms = √(3RT/M), hence v_rms is proportional to √T.

  4. Question 4

    Q4. A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If the work done by the system is 750 J, the heat transferred to the system is

    • A) -1250 J
    • B) 250 J
    • C) -250 J
    • D) 1250 J

    Answer: 250 J

    Explanation: ΔU = Q - W, so Q = ΔU + W = -500 + 750 = 250 J. But since the internal energy decreases, the system loses heat, hence Q = -250 J.

  5. Question 5

    Q5. The specific heat capacity at constant volume (Cv) for an ideal monoatomic gas is

    • A) (3/2)R
    • B) (5/2)R
    • C) R
    • D) (7/2)R

    Answer: (3/2)R

    Explanation: For a monoatomic ideal gas, Cv = (3/2)R, where R is the gas constant.

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