Question

If you fill your car tire to a pressure of 32 psi (pounds per square inch) on a hot summer day when the temperature is 35°C (95°F), what is the pressure (in psi) on a cold winter day when the temperature is -15°C (5°F)? Assume no gas leaks out between measurements and the volume of the tire does not change.

Answer 1

By Gay Lussacs law you can find the pressure. First both temperatures of Celsius must change to Kelvin by adding 273. Temperature one will be 308K and temperature 2 will be 258K
With this info, you can now find the pressure with Lussacs law

P1 = P2
— —
T1 T2

Pressure 1 is given which is 32 psi so just plug it all in and find P2

32 = x
—— ——
308 258

308x = 8256 (Cross multiply)

X = 26.8 (divide both sides by 308)

Answer is 26.8 PSI

This makes sense because as temperature increases pressure increases, as well as when temperature decreases, pressure decreases. Since it’s a colder day the pressure will be lower.