The menual of a car instructs the owner to inflate the tyres to pressure of 200 kPa. (a) What is the recommended gauge pressure ? (b) What is the recommended absolute pressure ? (c ) If after the required inflation of the tyres, the car is driven to a mountain peak. where the atmospheric pressrre is 10 % below that at sea level, what will be the tyre gauge read ? Atmospehric pressure ` =1.01 xx 10^5Pa.`

Explanation

(a) Pressure Instructed by manual = `P_(g) = 200 K P_(a)`
(b) Absolute Pressure = `101 k P_(a) + 200 k P_(a) = 301 k P_(a)`
At mountain Peak Pa′ is 10% less
`P_(a)=90 kP_(a)`
If we assume absolute pressure in tyre does not change during driving then
`P_(g) = P – P_(a)′ = 301 – 30 = 211 k P_(a)`
So the tyre will read 211 k `P_(a)`, pressure.