Calculate the work done. (a) Along path AB(b) Along path BC (c ) Along path CA (d) For the whole cycle. The indicator diagram, between P and V, is as shown.

Calculate the work done. (a) Along path AB(b) Along path BC (c ) Alo

1.	Calculate the work done. (a) Along path AB(b) Along path BC (c ) Along path CA (d) For the whole cycle. The indicator diagram, between P and V, is as shown.
Answer» <P> Solution :Word done is positive when gas expands and NEGATIVE when gas contracts. In P-V diagram, P is represented along y-axis and V is taken along x-axis. Work done is positive if the cycle is clockwise and work done is negative if cycle is anticlockwise. (a) Work done `= P xx "CHANGE in volume" Delta V` `W_(AB) = 20 xx (3-2) = 20 xx 1 = 20 J` (b) `W_(BC) = "Pressure" xx (3-3) = "zero"`. As there is no change of volume. (C ) `W_(CA)` = It is negative because volume decreases. = -Area of CALMC= -Area of (ABC + ABML) `= -((1)/(2) xx 1 xx 20 + AB xx BM)` `= -(10 + 1 xx 20) = -30 J` (d) For whole cycle, work done = -area of `Delta ABC = -(1 xx 20)/(2)` `:.` work done for whole cycle = -10 J Note : For whole cycle, we may consider `W_(AB) + W_(BC) + W_(CA)` also.