Cylinder gas, pressure question

In summary, Rory is trying to calculate the new pressure after the piston is compressed. He doesn't know how to do it and needs help from someone more experienced.
  • #1
yopy
43
0
http://img15.imageshack.us/img15/9746/21478397.png [Broken]

I know how to setup the entire problem i just don't know how to calculate the new pressure after the piston is compressed.
 
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  • #2
yopy said:
I know how to setup the entire problem i just don't know how to calculate the new pressure after the piston is compressed.

PV = nRT

n, R, T remain the same. They give you everything else.
 
  • #3
LowlyPion said:
PV = nRT

n, R, T remain the same. They give you everything else.

how do i calculate the number of moles?
 
  • #4
maybe p1v1/t1 = p2v2/t2 is more appropriate?
 
  • #5
RoryP said:
maybe p1v1/t1 = p2v2/t2 is more appropriate?

i don't think so, this is actually from my physics class and we never covered that
 
  • #6
ok fair enough
just out of interest is the answer 234375 Pa?
 
  • #7
What Rory is saying is that PV = nRT is the general equation but nRT and are constant
So p1v1 = p2v2, rearrange a little and you have the answer
 
  • #8
RoryP said:
ok fair enough
just out of interest is the answer 234375 Pa?

not sure, has yet to be handed in
 
  • #9
ahhh yes even more simple! forgot the temperature remained constant!
ok fair enough, would you be as kind enough to tell us the answer as i am revising for my physics A-level at the minute so all questions are useful!
 
  • #10
RoryP said:
just out of interest is the answer 234375 Pa?
No.

The volume goes from 0.750 -> 0.480 m^3, the pressure starts at 1.50 x10^5 Pa
so the final pressure is (0.750/0.480) * 1.50 x10^5 Pa = 2.34 x10^5 pa

You understand why your answer is wrong?
 
  • #11
mgb_phys said:
No.

The volume goes from 0.750 -> 0.480 m^3, the pressure starts at 1.50 x10^5 Pa
so the final pressure is (0.750/0.480) * 1.50 x10^5 Pa = 2.34 x10^5 pa

You understand why your answer is wrong?

lol that's the answer i got, except yours is in standard form! lol
 
  • #12
This is a 'physics' A level not maths
2.34 x10^5 is correct 234375.000000000000000000000 pa is wrong - whatever your calculator says!

Hint, what's the precision of the initial pressure measurment
 
  • #13
oooohhh slightly harsh!
but never the less that's fair enough!
no wonder my physics teacher is always annoyed with me for leaving whole answers!
 
  • #14
RoryP said:
maybe p1v1/t1 = p2v2/t2 is more appropriate?

yea this is the correct way to do it, thanks
 
  • #15
RoryP said:
ahhh yes even more simple! forgot the temperature remained constant!
ok fair enough, would you be as kind enough to tell us the answer as i am revising for my physics A-level at the minute so all questions are useful!

http://wug.physics.uiuc.edu/cc/IAState/Phys221/spring/homework/written%20homework/index.html [Broken]


have at it.
 
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1. What is cylinder gas?

Cylinder gas is a compressed gas that is stored and transported in pressurized containers. It is commonly used for industrial and medical purposes, such as welding, refrigeration, and anesthesia.

2. How is cylinder gas pressurized?

Cylinder gas is pressurized by compressing the gas into a smaller volume, which increases the pressure. This is usually done using a compressor or a high-pressure pump.

3. What factors affect the pressure of cylinder gas?

The pressure of cylinder gas is affected by the temperature, volume, and amount of gas inside the cylinder. The type of gas and the type of cylinder also play a role in determining the pressure.

4. How is the pressure of cylinder gas measured?

The pressure of cylinder gas is typically measured in units of pounds per square inch (psi) or kilopascals (kPa). This can be done using a pressure gauge or a manometer.

5. What precautions should be taken when handling cylinder gas?

When handling cylinder gas, it is important to follow safety guidelines and handle the cylinders carefully. This includes storing them in a well-ventilated area, avoiding exposure to heat or flames, and using the appropriate safety equipment when handling or using the gas.

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