Question

Calculate the net work done to the environment during one cycle of a particular heat engine. The cycle is shown by the closed curve on the PV diagram. The direction of the process is shown by the arrow. The unit of volume is m^3, the unit of pressure is 10^5 ps.

Answer 1

W = -P*$\Delta V$

Where

W stands for work done

P stands for pressure

$\Delta V$ for change in volume

l pressure is 10' Pa. 2.0 2.5 5.0

For 1

W = Area under the line which is the sum of area of triangle and rectangle below it

W = 0.5*1.5*10⁵*2.5 + 2*10⁵*2.5 = 187500 + 500000 = 687500 J

Since volume is increasing it will be negative

For 2

It will be the area of the rectangle = 500000J

Since volume is decreasing work will be positive

For 3

Work done is zero as there is no change in volume

Hence net work done

-687500 + 500000 = -187500 J