How Much Work is Done Moving Fluid Between Two Cylinders?

[bdumper]

A student exerts a steady force on the piston of her "master cylinder" and observes that it moves downward 3.2 cm as 10 ml of fluid moves into the "slave cylinder" and lifts a 500 g mass. She then reverses the roles of "master" and "slave" and places the 500 g mass on the piston of what originally was the master cylinder and finds that a constant force of 21 N is required to move the piston downward 2.3 cm. and return the 10 ml of fluid to it's original cylinder.

How much work (in Joules) did she do in the first case to move 10 ml of fluid from the "master" cylinder to the "slave" cylinder?


I tried using the equation F1/F2=A1/A2 where I put in 21N for F2 and I put in .01L for A1 and A2 but that was not the right answer.

I think I am supposed to use this equation but I must be putting in wrong A values. My train-of-thought was the area is equal to the amount of liquid which was moved from one piston to the other which was 10 ml.

Please help me figure out where I can go from here to solve the equation.

Thanks

 

[jbsteele]

!The correct equation that you should use is W = F x d, where W is the work done, F is the force applied and d is the distance moved. In the first case, the force is the weight of the 500 g mass, which is equal to 0.5 kg x 9.8 m/s2 = 4.9 N. The distance moved is 3.2 cm, or 0.032 m. Therefore, the work done in the first case is 4.9 N x 0.032 m = 0.154 J.