A car is to be lifted by a hydraulic jack which consists of two pistons. The large piston is 80 cm in diameter and the smaller piston is 16 cm in diameter. If W is the weight of the car, then how much smaller force is needed on small pistonto lift the car?

Explanation

Radius of large piston , `R_(2)= 40 cm =0.40 m`
Radius of small piston , `R_(1) = 8 cm =0.08 m`
`F_(2) =W , F_(1)= ?`
Ac cording to Pascal's law `(F_1)/(pi R_(1)^(2)) = (F_2)/(pi R_(2)^(2))`
or, `F_(1) = F_(2) (R_(1)^(2))/(R_(2)^(2)) = W xx ((0.08)/(0.40))^(2) = 0.04 W`.
`= 4% ` of the weight of car.