physics
posted by kate .
You are designing a hydraulic lift for an automobile garage. It will consist of two oilfilled cylindrical pipes of different diameters. A worker pushes down on a piston at one end, raising the car on a platform at the other end. To handle a full range of jobs, you must be able to lift cars up to 4000kg, plus the 600 kg platform on which they are parked. To avoid injury to your workers, the maximum amount of force a worker should need to exert is 100N.What should be the diameter of the pipe under the platform?
Can someone please explain how i should do this problem I have no idea

The maximum weight that has to be lifted is (4000 + 600) g = 45,080 N. The force applied to the other piston must must not exceed 100 N. The ratio of the diameters of the two pistons must be sqrt (45080/100) = 21.2
You seem to be missing an important piece of information: the diameter of the smaller piston that is "pushed" by the operator. 
25cm is the other operator

Then multiply that diameter by 21.2 to get the diameter of the piston that lifts the car and platform..