The mean speed of molecules escaping from the atmosphere of a planet into outer space is greater than the mean speed of molecules that remain in the atmosphere.

Question

Quizplus · Accepted Answer

Molecules that escape a planet's atmosphere (exosphere) must have a speed greater than or equal to the escape velocity of the planet, which is higher than the average speed of molecules remaining in the atmosphere. This is because only the fastest molecules, with enough kinetic energy, can overcome the planet's gravitational pull.

The Mean Speed of Molecules Escaping from the Atmosphere of a Planet