Calculating Work and Input Force for a Hydraulic Lift

[jaco9115]

Homework Statement

A hydraulic lift is used to jack a 970-kg car 12 cm off the floor. The diameter of the output piston is 18 cm, and the input force is 250 N. (A) What is the area of the input piston? (B) What is the work done in lifting the car 12 cm?

Homework Equations

Fo=mg m=mass of car g=gravity

Fi/Ai=Fo/Ao

The Attempt at a Solution

250N/Ai=mg/Ao

250N/x^2=mg/.18^2


Do I just need to solve for x to find solution "A". I am also having trouble getting started with "B", do I need to find "A" first?


Also, sorry if I posted this in the wrong spot. I am new to this and didn't really know how to go about posting. Thanks.

 

[jaco9115]

I have start on "B"

W=(F2)(y)= ??

y=.12 m

Do I solve for F2?

 

[ideasrule]

Do I just need to solve for x to find solution "A".

Since you used 0.18^2 on the other side of the equation and 0.18 is a diameter, the x in x^2 would also represent diameter.

I am also having trouble getting started with "B", do I need to find "A" first?

No. There's a very simple formula for the energy it takes to lift an object against gravity.

 

[jaco9115]

For "B"...would the simple formula be (970)(9.8)(.12)? therefore 1140.72 J correct?

 

[ideasrule]

Yup.