At present, the measuring personnel use a laser rangefinder to send a pulsed laser beam to the moon and receive the reflected laser beam. They measure that the time for the laser to go back and forth is 2.54s. How many meters is the distance between the moon and the earth? (the speed of light in vacuum is 3 times 10 octave)

The distance between the earth and the moon is twice as long as the distance between the earth and the moon, so the distance between the earth and the moon is 2.54s × 3 × 10 ^ 8m / s △ 2 = 381000000 m, that is 381000 km

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1. The principle of laser rangefinder is understood. The distance can be calculated by calculating the time taken to receive the reflected laser, but what we don't understand is how to send it back? When a flashlight is used to irradiate a plane mirror three or four meters away, it will reflect back light, but when it is used to irradiate ordinary objects such as tables and stools (especially in the bright outdoor environment), it will not be seen that the light emitted by a flashlight will reflect back. Even the common laser lamp similar to a flashlight can not see the reflected light when it is three or four meters away in this environment, Is the reflection ability of the lunar surface so strong? How does the object reflect back the emitted beam or something else
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