途径B,分两步膨胀, 1)先反抗外压p1=2×105Pa 33333 膨胀到8dm3 W1=p外△V 2×105Pa×(8-4)×10-3m3 800J 2)再反抗外压p2=1×105Pa 膨胀到16dm3 1×105Pa p外△V 16dm3 1×105×(16-8)×10-3 800(J) 2×105Pa 4×105Pa Wa=W;+W,=800+800 8 dm 1600(J) 4 dmW1 = p外 V = 2 10 5 Pa ( 8 - 4 ) 10-3 m3 = 800 J 途径 B,分两步膨胀, 1 ) 先反抗外压 p1 = 2 10 5 Pa 膨胀到 8 dm3 2 10 5 Pa 8 dm3 WB = W1 + W2 = 800 + 800 = 1600 ( J ) W2 = p外 V = 1 10 5 ( 16 - 8 ) 10-3 = 800 (J) 1 10 5 Pa 16 dm3 4 10 5 Pa 4 dm3 2 ) 再反抗外压 p2 = 1 10 5 Pa 膨胀到 16 dm3