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| 1. |
Explain the reason why the Moon cannot retain its atmosphere. Take into account that during a lunar day its temperature rises above 100^@C. |
| Answer» Solution :At the TEMPERATURE of `100^@C` the root-mean-square velocity of the hydrogen molecules is `2.15 xx 10^3 m//s`. The escape velocity for the Moon is 2.4 km/s (see Problem 12.14). Naturally, the Moon.s gravitational field is UNABLE to RETAIN hydrogen. The root-mean-square VELOCITIES of molecules of other gases are several times smaller. But in ACCORDANCE with the Maxwell distribution there is always a considerable fraction of the molecules whose velocity is several times the average (see `xi` 25.2). Because of this Moon.s gravitational field is also unable to retain other gases, and they disperse in space. | |