How Does Temperature Affect Tire Pressure?

[zcabral]

Homework Statement

An automobile tire is inflated with air originally at 10.0°C and normal atmospheric pressure. During the process, the air is compressed to 26.0% of its original volume and the temperature is increased to 32.0°C.
(a) What is the tire pressure?

Homework Equations

p1V1/t1=p2v2/t2

The Attempt at a Solution

i know this is simple but I am just not getting the right answer I keep using p1V1/t1=p2v2/t2 but wrong answers come out. i used 1 atm for normal atmospheric pressure

 

[mgb_phys]

Remember that T must be in Kelvin since you are dividing by it.

 

[zcabral]

yes it is in kelvin...i got 419903.5 is that right?

 

[mgb_phys]

First estimate the answer!
Temperature hasn't changed much in absolute terms
volume has gone down by a factor of 4 - so we want a pressure of around 4 atm.

V1 = 1
V2 = 0.26
P1 = 1atm
T1 = 283K
P2 = ?
T2 = 305K

1/283 = 0.26 P /305
So P = (305 /283) / 0.26 = 4.1 atm or around 420KPa

ps. That's an impressive number of significant figures given the data!

 

[zcabral]

it asks for it in pa that's y