NEET-XII-Physics

26: Laws of Thermodynamics

with Solutions - page 3
Qstn# iv-5-a Prvs-QstnNext-Qstn
  • #5-a
    Calculate the work done by the gas. (b) If no heat is supplied or extracted from the gas, what is the change in the internal energy of the gas? (b) If no heat is supplied or extracted from the gas, what is the change in the internal energy of the gas?
    Ans : Work done on the gas = Pressure `` \times `` Change in volume of the system
    Since pressure is also changing, we take the average of the given two pressures.
    Now,
    P = `` \left(\frac{1}{2}\right)\left(10+50\right)\times {10}^{3}``
    = `` 30\times {10}^{3}`` Pa
    Work done by the system of gas can be given by
    `` 30\times {10}^{3}\times \left(50-200\right)\times {10}^{-6}``
    `` =-4.5\,\mathrm{\,J\,}`` (b) Since no heat is supplied to the system, ∆Q = 0.
    Using the first law of thermodynamics, we get
    ∆U = - ∆W = 4.5 J
    Page No 62: (b) Since no heat is supplied to the system, ∆Q = 0.
    Using the first law of thermodynamics, we get
    ∆U = - ∆W = 4.5 J
    Page No 62:
  • #5-b
    If no heat is supplied or extracted from the gas, what is the change in the internal energy of the gas?
    Ans : Since no heat is supplied to the system, ∆Q = 0.
    Using the first law of thermodynamics, we get
    ∆U = - ∆W = 4.5 J
    Page No 62: