Calculating Tire Pressure Change After a Drive

[mawalker]

On a cool morning, when the temperature is 16.0 C, you measure the pressure in your car tires to be 20.0 psi. After driving 50.0 mi on the freeway, the temperature of your tires is 38.0 C. What pressure will your tire gauge now show?

I have Ti = 289 K
Tf = 311 K
R = 8.31 pressure constant
pinitial = 1.36 atmosphere
n = ?
V = ?
I'm lost...

 

[OlderDan]

On a cool morning, when the temperature is 16.0 C, you measure the pressure in your car tires to be 20.0 psi. After driving 50.0 mi on the freeway, the temperature of your tires is 38.0 C. What pressure will your tire gauge now show?

I have Ti = 289 K
Tf = 311 K
R = 8.31 pressure constant
pinitial = 1.36 atmosphere
n = ?
V = ?
I'm lost...

You are not adding any air, so what happens to n? You can assume the volume does not change. You might need to think about what a tire gauge actually measures.

 

[Meir Achuz]

On a cool morning, when the temperature is 16.0 C, you measure the pressure in your car tires to be 20.0 psi. After driving 50.0 mi on the freeway, the temperature of your tires is 38.0 C. What pressure will your tire gauge now show?

I have Ti = 289 K
Tf = 311 K
R = 8.31 pressure constant
pinitial = 1.36 atmosphere
n = ?
V = ?
I'm lost...

Use proportions: pf/pi=Tf/Ti.