Moon landing time = (20/0.8) under the root sign = 5 seconds.
(2) As can be seen from the above calculation, the same 20 meters takes only 2 seconds on the earth and 5 seconds on the moon, so it can be seen that objects fall faster on the earth. More generally, because the acceleration of gravity on the earth is almost six times that on the moon, the time to fall at the same height on the moon is the square root of six, which is nearly 2.5 times. (The square root of 6 is about 2.449)