pV=constant so 2.5x1000=2500=pV=1xV so V=2500cm^3
The air had volume of 2500 at 1atmosphere but we put in an extra 100 so new volume at 1 atmosphere is 2600cm^3
pV=1X2600=px1000 so p=2.6 atmospheres.
I tried the same thing earlier but the answer to this question is 1.1 atmospheres. How do you derive that?
And this question was found in a physics textbook for IGCSE known as Physics For You by Keith Johnson. I don't know whether it was taken from any past paper.
anyways thanks for your help.
How can youn pump in 100cm^3 more air and have the pressure fall from 2.5 to 1 atmosphere?
I'll answer the question I posted. I know that's absurd but it's just to make sure others reading it do not get it wrong.
Q. a)The air in a bicycle tyre has a volume of 1000cm
3 and a pressure of 2.5 atmospheres. If the air is released ( at the same temperature) so its pressure is 1 atmosphere, what is the volume of the air?
b)A bicycle has a volume of 100cm
3 and is now used to pump up the tyre. After 1 stroke of the pump, what is the presure in the tyre?
Ans:
(a) V1= 1000 cm
3, P1= 2.5 atm. V2= ?, P2= 1 atm.
Using Boyle’s Law,
P1V1 = P2V2
V2 = P1V1/P2
= 2500 cm
3 (b) According to Boyle’s law,
Pressure and volume is inversely proportional to each other,
Hence if volume decreases, the pressure increases but in same ratio,
Since the volume of the pump is 100 cm
3, and volume of the tyre is 1000cm
3, the ratio of the decrease in volume after one stroke = 100/1000=0.1
Hence the ratio by which the pressure will increase is 0.1 atm.
Hence total pressure in the tyre = 1 atm + 0.1 atm
= 1.1 atm