posted by Zach .
A hydraulic jack is designed so that when the handle is pushed down 1 m, the piston raising the load moves up 0.015 m.
At this efficiency, what is the force required to lift a 5000 N weight?
The ideal mechanical advantage is
1/0.015 = 66.67 They tell you that already.
Because of inefficiency (friction), you have to apply
1/26.67 times the lifted weight, or 187.5 N