A tyre pressure gauge indicates 20 N/cm2 for a tire at 34°C after a fast motorway run. Assuming that the volume of the air in the tyre is constant, atmospheric pressure is 760 mmHg and the air gas constant is 0.287 kJ/kg.K:
i) Estimate the indicated pressure when the tyre has cooled to 10°C.
ii) If the tyre is treated as a tube of cross-sectional area 0.015 m2 rolled into a ring of mean diameter 0.035 m, estimate the mass of air in the tyre.
Combined Gas Law:
Equation of State for Ideal Gas:
[tex]pV = mRT[/tex]
The Attempt at a Solution
Converting units into SI and recognising volume = constant gives:
[tex]p_2 = 184kPa[/tex]
I am unsure how exactly how to proceed with ii)
Any help would be appreciated.