The Volcanic Escape Pod · AI Generator #GEN-1E7A46D5

Physics · thermodynamics

Problem

A cylindrical escape pod with volume V=8.0  m3V = 8.0\;\text{m}^3 is designed to protect researchers from volcanic eruptions. The pod is sealed at atmospheric pressure P0=1.0×105  PaP_0 = 1.0 \times 10^5\;\text{Pa} and temperature T0=300  KT_0 = 300\;\text{K}. During an eruption, the pod is rapidly heated by lava flow to a temperature of T1=450  KT_1 = 450\;\text{K}. The pod is equipped with an emergency pressure relief valve that opens when the internal pressure exceeds Pmax=2.5×105  PaP_{max} = 2.5 \times 10^5\;\text{Pa}. After the valve opens, hot air escapes until the pressure drops back to PmaxP_{max}, then the valve closes. The pod then continues to heat up until the valve opens again. Assume the heating process is slow enough that the gas remains in thermal equilibrium with the pod walls at all times, and treat air as an ideal gas. What fraction of the original air mass remains in the pod after the first valve opening cycle?
Intuitive explanation

This problem combines the ideal gas law with a multi-step process: first, the sealed pod heats up and pressure rises; then, when the relief valve opens, air escapes at constant pressure until the valve closes; finally, you need to compare how many moles (or mass) of air remain versus what started inside. The key insight is that the number of moles is proportional to PV/TPV/T, so you can track the gas amount before and after the valve cycle using this ratio—no need to find absolute densities.

Intuitive explanation

This problem combines the ideal gas law with a multi-step process: first, the sealed pod heats up and pressure rises; then, when the relief valve opens, air escapes at constant pressure until the valve closes; finally, you need to compare how many moles (or mass) of air remain versus what started inside. The key insight is that the number of moles is proportional to PV/TPV/T, so you can track the gas amount before and after the valve cycle using this ratio—no need to find absolute densities.

Related theory

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