NEET-XII-Physics
26: Laws of Thermodynamics
- #1-aHow much heat is transferred to the liquid-vessel system? (b) How much work has been done on this system? (c) How much is the increase in internal energy of the system?Ans : Since the system is insulated from the surroundings, no heat is transferred between the system and the surroundings. This implies that the heat transferred to the liquid vessel system is zero. The internal heat is shared between the vessel and water. (b) Work done on the system`` ={m}_{w}{c}_{w}∆t+{m}_{v}{c}_{u}∆t``
⇒ dW = 100 × 10-3 × 420 × 2 + 200 × 10-3 × 4200 × 2
⇒ dW = 84 + 84 × 20 = 84 × 21
⇒ dW = 1764 J (c) Using the first law of thermodynamics, we get
`` dQ=dW+dU``
`` \,\mathrm{\,Here\,},dW=pdV``
Work is done by the system. Thus, work done is negative.
⇒ dQ = 0 (given)
dU = - dW
= `` -``(`` -``1764) = 1764 J
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- #1-bHow much work has been done on this system?Ans : Work done on the system`` ={m}_{w}{c}_{w}∆t+{m}_{v}{c}_{u}∆t``
⇒ dW = 100 × 10-3 × 420 × 2 + 200 × 10-3 × 4200 × 2
⇒ dW = 84 + 84 × 20 = 84 × 21
⇒ dW = 1764 J
- #1-cHow much is the increase in internal energy of the system?Ans : Using the first law of thermodynamics, we get
`` dQ=dW+dU``
`` \,\mathrm{\,Here\,},dW=pdV``
Work is done by the system. Thus, work done is negative.
⇒ dQ = 0 (given)
dU = - dW
= `` -``(`` -``1764) = 1764 J
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