By measuring the go-and-return time for a laser pulse to travel from an Earth-bound observatory to a reflector on the Moon, it is possible to measure the separation between these bodies.
(a) What is the predicted value of this time?
(b) The separation can be measured to a precision of about 21 cm. To what uncertainty in travel time does this correspond?
(c) If the laser beam forms a spot on the Moon 4.22 km in diameter, what is the angular divergence of the beam? Give Your answers with units please?