A tire contains air at a gauge pressure of 33.8 lb/in^2 at a temperature of 30.9 C. After nightfall, the temperature drops to -12.9 C. Find the new gauge pressure in the tire, assuming that the volume of the tire remains constant during this process in units of lb/in^2.
1 atm=14.7 lb/in^2
2007-12-03 11:10:41 · 1 answers · asked by snow200098 2 in Science & Mathematics ➔ Physics
Gay-Lussac discovered the law that says the pressure of a fixed amount of gas at fixed volume is directly proportional to its temperature in kelvins.
http://en.wikipedia.org/wiki/Gay-Lussac%27s_law
So: P1/T1 = P2/T2
The reason you need to know atmospheric pressure is that the equation uses absolute pressure, while the gauge measures the difference between the pressure inside the tire and the atmospheric pressure.
http://en.wikipedia.org/wiki/Pressure
So you can compute P1 (absolute pressure), T1, and T2 (in degrees Kelvin) and so find P2. Then convert the absolute pressure of P2 back to gauge pressure.
2007-12-04 17:02:10 · answer #1 · answered by simplicitus 7 · 0⤊ 0⤋