What is the necessary force to support a 500 lb weight with a hydraulic lift?

[Izmad]

Homework Statement

Piston 1 in Figure P9.24 has a diameter of 0.32 in.; Piston 2 has a diameter of 2.0 in. In the absence of friction, determine the force, , necessary to support the 500 lb weight.

Picture
http://www.webassign.net/sf/p9_24.gif

Homework Equations

F1=(A1/A2)F2
A=pi*r^2

The Attempt at a Solution

I solved for F1 using the above equation and got 12.8. THIS IS WRONG Is this because the column of fluid is higher in the larger piston? So i have to factor in the weight of the higher water as well? Can someone please point me in the correct direction?

thanks

 

[learningphysics]

you got the force that the piston at 1 exerts upwards... what force does the hand need to exert to keep the piston from moving.. use torque.

 

[Izmad]

torque=rF

would the radius be from the hand to the center of piston 1?

 

[learningphysics]

torque=rF

would the radius be from the hand to the center of piston 1?

you want the torque about the point next to the piston 2. so torque due to the F force is F*12.0in clockwise... what is the torque due to the pressure force...