volume_mute

Effect of Decreasing Volume on Pressure

publish date: 2026/05/19 08:28:36.872915 UTC

volume_mute

If a fixed mass of gas is confined inside a cylinder and the piston is pushed down to decrease the volume to exactly half its original space at a constant temperature, how does the molecular collision rate and pressure change?

The molecules are crowded into half the space, doubling the collision frequency against the walls and doubling the pressure.

The molecules slow down due to the restriction, causing the pressure to drop to half its original value.

The molecules fuse together, leaving the total number of wall impacts and pressure unchanged.

The collision frequency doubles, but the pressure drops because the molecules lose kinetic energy.

Correct Answer

The molecules are crowded into half the space, doubling the collision frequency against the walls and doubling the pressure.

Explanation

Halving the volume means the same number of molecules occupy half the space. Consequently, they strike the container walls twice as often per unit area, resulting in a doubling of the total pressure.

Reference

Basic Physics: A Self-Teaching Guide

Quizzes you can take where this question appears

Molecules in gases