A hydraulic jack has pistons 2.0 cm and 25 cm across…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A hydraulic jack has pistons and across. What force on the small piston holds up a van? How far must the small piston move in all to raise the van by ? (.)
Need a reminder? The key ideaShow
Pressure is force per unit area, , in pascal. Below the surface of a liquid, ; the gauge pressure is . Pascal's law: a change of pressure in an enclosed fluid reaches every part of it, so a hydraulic machine gives .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Area ratio. .
Step 2. Force. .
Step 3. Distance. , in many short strokes.
Answer: ; of pumping in all.
Check. Work in: ; work out: .
Watch out. Square the ratio of the diameters.
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