# What stress needs to be exerted to turn a quart of water into a pint?

1. Apr 14, 2012

### jami8337

1. The problem statement, all variables and given/known data
Dr Stewart’s Aunt Sally was constantly reminding him that he couldn’t squeeze a
quart (946 ml) into a pint pot (473 ml). Annoyed by this negative attitude, he set
about proving old Sally wrong. He constructed a platform, resting on a steel piston
radius 1 mm, length 10 m, bearing down on a chamber of equal radius, containing
1 quart of water. He then placed a number of 1000 kg elephants, procured from the
local zoo, on the platform.
What stress needs to be exerted to turn a quart of water into a pint?

2. Relevant equations
B=-P/(dv/v)
stress = F/A

3. The attempt at a solution

2.2Gpa(473/946)=P
=1.1*10^9

Not really sure what to do from here...

2. Apr 14, 2012

### OldEngr63

Hope that the zoo has a lot of elephants available. Water is very nearly incompressible. You are looking at a 50% reduction in volume which is going to require extreme pressure, very extreme pressure!

3. Apr 14, 2012

### D H

Staff Emeritus
Do the math. Not even one elephant is needed. And these are small elephants.

That's assuming this piston or cylinder could exist. Both would have to be made of unobtanium.