Question

When a system is taken from state i to state f along the path iaf, it is found that `Q=50 cal and W=20 cal`. Along the path ibf `Q=36cal`. W along the path ibf is

A. `6 cal`
B. `16 cal`
C. `66cal`
D. `14cal`

Answer 1

Correct Answer - A
From first law of thermodynamics,
`Q = DeltaU +W`
For path iaf,
`50 = DeltaU +20`
`:. DeltaU = U_(f) - U_(i) = 30 cal`
For path ibf,
or `Q = DeltaU +W`
`W = Q - DeltaU = 36 - 30 = 6cal`.