(a) Compute the escape speed of a particle from the Earth's surface. Earth's radius is 6378 km, and its mass is 5.98 X 1024 kg.
(b) Find the mean speed for a helium atom at a temperature of 293 K.
(c) Comment on the fact that your answer to (b) is less than the answer to (a). Why then does helium not remain in the atmosphere in signi?cant quantities?