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astarmathsandphysics:
Ok then that would be your method. Having measured the distance with a compass, you can find the distance by lining the compass up with a ruler.
SGVaibhav:
hmm
i think i am not able to express my question clearly.
i will show u the link to the exact question, that will help
http://www.freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvUGh5c2ljcy9DSUUvMjAwMiBOb3YvMDYyNV93MDJfcXBfNi5wZGY=
Q5)b) (can u show me atleast 2 methods please)
Thanx
:D
nid404:
--- Quote from: astarmathsandphysics on April 22, 2009, 11:06:58 am ---
--- Quote from: nid404 on April 22, 2009, 09:56:51 am ---
--- Quote ---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.
--- End quote ---
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.
--- End quote ---
How can youn pump in 100cm^3 more air and have the pressure fall from 2.5 to 1 atmosphere?
--- End quote ---
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 1000cm3 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 100cm3 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 cm3, P1= 2.5 atm. V2= ?, P2= 1 atm.
Using Boyle’s Law,
P1V1 = P2V2
V2 = P1V1/P2
= 2500 cm3
(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 cm3, and volume of the tyre is 1000cm3, 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
astarmathsandphysics:
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
THE AIR IN THE TYRE IS NEVER AT A PRESSURE OF 1 ATM. IT IS 2.5 ATM
Sorry to write in capitals but I had to make you read this.
astarmathsandphysics:
It is only a 1 mark question. Why do you have nightmares? Use a meter rule either on the bench or in a clamp.
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