Question

PLEASE SHOW YOUR WORK. THANK YOU.

P ( kPa) 1200 1100 1000 900 800 700 600 500 400 300 200 100 v (m2) 1 2 3 4 5 6 7 8 9

(a) Find the work done by an ideal gas as it expands from point A to point B along the path shown in the figure.
_____MJ

(b) How much work is done by the gas if it compressed from B to A along the same path?

____ MJ

Answer 1

P (kPa) 1200 1100 1000 900 800 700 600 500 400 300 200 100 v (m2) 12 3 4 5 6 78 9

a)
since it is expanding, work done by it is positive
Work done = area under the curve
= area of reactangle I + area of trapezium II + area of trapezium III + area of reactangle IV
= 200*(4-3) + 0.5*(6-4)*(1100+200) + 0.5*(7-6)*(1100+800) + 800*(8-7) KPa*m^3

Since area of rectangle = Length * breadth
Area of trapezium = 0.5*(base 1 + base 2)* height

Work done = 200 + 1300 + 950 + 800 KJ
= 3250 KJ
Answer: 3250 KJ

b)
Since it is compressing, work done by it is positive
Answer: -3250 KJ