45. (a) One part of path A represents a constant pressure process. The volume changes from 1.0 m 3 to 4.0 m 3 while the pressure remains at 40 Pa. The work done is 33 2 (40Pa)(4.0m 1.0m ) 1.2 10 J. A Wp V =Δ= − = × (b) The other part of the path represents a constant volume process. No work is done during this process. The total work done over the entire path is 120 J. To find the work done over path B we need to know the pressure as a function of volume. Then, we can evaluate the integral W= ³p dV. According to the graph, the pressure is a linear function of the volume, so we may write p = a+ bV , where a and b are constants. In order for the pressure to be 40 Pa when the volume is 1.0 m 3and 10 Pa when the volume is 4.00 m 3the values of the constants must be
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