Example 4
An automobile tire is filled to a gauge pressure of `200\ kPa` at `10°C`. After a drive of `100\ km`, the temperature within the tire rises to `40°C`. What is the pressure within the tire now?
Given:
`T_1 = 10°C = 283 K`
`P_1 = 200 kPa + 101\ kPa = 301\ kPa`
`T_2 = 40°C = 313 K`
`P_2 = ?`
Equation: `PV = nRT`
Solution:
For fixed amount of gas, `nR` is a constant. Thus, `(PV)/T=` constant. or
`(P_1V_1)/T_1 = (P_2V_2)/T_2`
In this problem, we consider the volume inside the tire will not change. then
`(P_1V)/T_1 = (P_2V)/T_2 => P_1/T_1 = P_2/T_2 `
`P_2 = P_1T_2/T_2`
`P_2 = (301\ kPa)(313 K)/(283 K)`
`P_2 = 333 kPa`
The gauge pressure will be `333\ kPa - 101\ kPa = 232\ kPa`