Question

Air is pumped into an automobile tube upto a pressure of 200 kPa in the morning when the air temperature is 22°C. During the day, temperature rises to 42°C and the tube expands by 2%. The pressure of the air in the tube at this temperature, will be approximately

• A. 212 kPa
• B. 209 kPa
• C. 206 kPa
• D. 200 kPa

Answer 1

Answer: (B)

209 kPa

Answer 2

$\frac{PV}{T} = R$ (constant) Ž $\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}$

Ž $\frac{200 \times V}{(273 + 22)} = \frac{P_{2} \times 1.02V}{(273 + 42)}$ $(V_{2} = V + 0.02V)$

Ž $P_{2} = \frac{200 \times 315}{295 \times 1.02} = 209kPa$