# Homework Help: Hydraulic break problem

1. Nov 2, 2012

### Douna2nd

A car service station uses a hydraulic car lift, the diameter of its pistons are 0.02 m and 0.32 m calculate the pressure required to raise a car of mass 1800 KG
I don't know how to get the area ?

2. Nov 2, 2012

### SteamKing

Staff Emeritus
Key words: piston, diameter

3. Nov 2, 2012

### Douna2nd

Area = pi times diameter square over 4?? And I'm gonna put the diameter of the larger pistol eh?

4. Nov 2, 2012

### SteamKing

Staff Emeritus
The larger diameter piston supports the weight of the car. The problem is asking you how much pressure must be applied to the smaller piston (assuming the smaller and larger pistons are connected hydraulically) to support the weight of the car.

5. Nov 3, 2012

### Douna2nd

The pressure on the small piston is equal to the pressure of the large piston so I'm gonna calculate the pressure of the large piston by the rule F/A force =mg where g is the force of gravity and area = pi diameter square over 4 ?

6. Nov 3, 2012

### haruspex

Sure, but I note that you don't need to know the smaller diameter for that. I would have expected the question to ask for the force needed. Maybe it asks for that later?