In a car lift compressed air exerts a force F`F_1` on a small piston having a radius of 5.0 cm, This pressure is transmitted to a second piston of radius 15cm [Fig.10.7]. If the mass of the car to be lifted is 1350 kg. calculate `F_1` What is the pressure necessary to accomplish this task?

Explanation

Since pressure is transmitted undiminished throughout the fluid,
`F_1=A_1/A_2 F_2=(pi(5 times 10^-2 m)^2)/(pi(15 times 10^-2 m)^2)(1350 kg times 9.8 ms^-2)`
=1470 N
`=1.5 times 10^3 N`
The air pressure that will produce this force is
`P=F_1/A_1=(1.5 times 10^3 N)/(pi(5 times 10^-2)^2 m)=1.9 times 10^5 Pa`
This is almost double the atmospheric pressure.
Hydraulic brakes in automobiles also work on the same principle. When we apply a little force on the pedal with our foot the master piston.