Imagine that, going to the exam, you decided to measure the pressure in a tire o
ID: 1852982 • Letter: I
Question
Imagine that, going to the exam, you decided to measure the pressure in a tire of your car. The pressure gauge showed 200 kPa. The thermometer and barometer in your garage showed 20 degree C and 900 mbar. respectively. After the exam, you decided to relax by driving to Las Cruces and back with an average speed of 50 mph. After your return, you again measured the pressure in the same tire and found that the pressure gauge showed 240 kPa. You also noticed that the thermometer and barometer showed the same temperature and pressure. Assuming that air is an ideal gas. the volume of the tire was 20 L and it did not change for the period between the two measurements, determine (a) the air temperature in the tire after the trip and (b) the mass of air that must be bled off to restore pressure to its original value.Explanation / Answer
Initial state,
P = 290 kPa
V =20 l
T= 20 C = 293 K
Final state,
n and R is constant.
P = 330 kPa
V = 20 l
T= ? ?
using ideal gas equation,
PV/T = P2V2 / T2
=> 290*20/293 = 330*20/T2
=>final temp = T2 = 333.4 K = 60.4 celsius