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| Temperature vs Pressure vs Volume Problems | |
| # h2phyt1 - Pressure and Volume | |
The chamber in a bicycle pump contains air at standard atmospheric
pressure. The valve is closed so no air escapes, and a downward push
of the handle decreases the volume of the air by 30 percent. What is the
new pressure of air in the chamber (assume no temperature change)
| Strategy - the rule "Must have" of Mr.Zhang ® |
| Boyle's law; | |||
| V | ∝ |
1
P
| |
| V | = | C x |
1
P
|
| PV | = | C | |
| P1V1 | = | P2V2 | → (1) |
***Both sides must be equal to the same constant.
| P1 is standard atmospheric pressure | = | 1.013x105 pa |
| = | 1 atm | |
| = | 1.013x105 N.m-2 |
= 760 mmHg
= 76 cmHg
= 29.9 in.Hg
= 760 torr
= 1013.25 mb
| Solution |
| Compute the new pressure from equation(1) |
| V2 | = | (100-30)%V1 | = | 70%V1 | = | 0.70V1 |
| P1V1 | = | P2V2 |
| (1.013x105 pa) |
= P2(0.70 |
(1.013x105 pa)
0.70
|
= | P2 |
| P2 | = | 0.144x106 pa |
| Ans. New pressure of air in the chamber is |
|
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