posted by Cuzzy .
A basketball is inflated in a garage at 25 degrees C to a gauge pressure of 8.0 psi. Gauge pressure is the pressure above atmospheric pressure, which is 14.7 psi. The ball is used on the driveway at a temperature of -7 degrees C and feels flat. What is the actual pressure of the air in the ball? What is the gauge pressure?
I'm pretty sure I need to use P1V1/T1= P2T2/V2 for this problem, but how can you when both the pressure and volume are unknown? Also, I don't really get the idea of gauge pressure. To find my second answer, would I add 8.0 to the first answer?
The true pressure (absolute pressure) in the ball is gauage + atmospheric. Remember if the guage pressure was zero, there is still atmospheric pressure in the ball....it is NOT empty. Use true (absolute ) pressure in these problems.
Actual pressure P1 in the ball is 8 Plus atmospheric. You are solving for P2.
You can always use that formula. In this case you do not know P2.
Change all temps to Kelvins.