# Force necessary to support mass on Hydraulic Jack?

by jumpingjack90
Tags: force, hydraulic, jack, mass, support
 P: 14 1. The problem statement, all variables and given/known data Piston 1 in the figure has a diameter of 1.31 cm. distance of 2 in Piston 2 has a diameter of 7.91 cm. distance of 10 in In the absence of friction, determine the force F, necessary to support an object with a mass of 904 kg placed on piston 2. (Neglect the height difference between the bottom of the two pistons, and assume that the pistons are massless). 2. Relevant equations F1*d1 = Fp*d2, where d1 is the moment arm of F1, and d2 is the moment arm of Fp. 3. The attempt at a solution Fp = (F1*d1)/d2 (904)(9.81)/(pi)(0.003955)^2= F/(pi)(0.00655)^2 F=242.98 N which was incorrect. anyone have an idea of what I should do and what equation to use? Thanks!
 Mentor P: 12,074 I think we'll need to see the figure before we can help you out.
 P: 14 http://img6.imageshack.us/img6/7849/...56447261f7.gif this is the link for the picture.
 PF Gold P: 619 Force necessary to support mass on Hydraulic Jack? Neglecting the height difference means the pressure should be the same, thus $$F_1 A_1 = F_2 A_2$$ This is would be the force exerted on the small piston. You should know how to find the force needed by the hand from this.
Mentor
P: 12,074
 Quote by jumpingjack90 2. Relevant equations F1*d1 = Fp*d2, where d1 is the moment arm of F1, and d2 is the moment arm of Fp. 3. The attempt at a solution Fp = (F1*d1)/d2 (904)(9.81)/(pi)(0.003955)^2= F/(pi)(0.00655)^2 F=242.98 N which was incorrect. anyone have an idea of what I should do and what equation to use? Thanks!
You have correctly found F1, the force on the smaller piston. However, they are asking for Fp (labelled simply F in the figure), the force exerted by the hand.

You have the equation to find Fp given F1.
 P: 14 ok. I used the equation given and solved for Fp. I had (242.98)(pi*(0.03955)^2))/(pi)*(0.00655)^2=Fp=8858.92 N, which is also incorrect. what am I doing wrong?
 P: 14 nvm. I solved it! thanks everyone for your input!
P: 8
 Quote by jumpingjack90 nvm. I solved it! thanks everyone for your input!
how u solved it my friend?

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