# PSI Calculations

1. Sep 3, 2013

### daviddjh

Suppose you have a hollow cube with a volume of 504c3. The inside of the cube has a psi of 94 and is just air. Now suppose that a hole opened in the bottom of this cube with an area of 12.56cm2 that leads to a hollow cylinder that is 14 cm long with a radius of 2cm. Now how would you go about calculating the psi of this whole structure after the hole is opened, the air is released and the volume has changed.

2. Sep 4, 2013

### Staff: Mentor

Does the cylinder contain air at normal atmospheric pressure, or is it vacuum?

3. Sep 4, 2013

### daviddjh

The cylinder would have a vacuum inside it

4. Sep 4, 2013

### Staff: Mentor

OK - that makes it easy. Boyle's Law, $PV=c$ where $c$ is a constant, will get you an answer in short order.

(Boyle's Law would still get you there if the cylinder weren't a vacuum, but it would be more work).