Question

On July 19, 1969, the lunar orbit of Apollo 11 was adjusted to an average height of 172 kilometers above the Moon's surface. The radius of the Moon is 1840 kilometers, and the mass of the Moon is 7.3 x 1022 kilograms. At what speed did the spacecraft orbit the Moon? Include units in your answer. Answer must be in 3 significant digits.

Answer 1

In order to calculate the speed of the spacecraft, use the following formula;

`v=\sqrt[]{(GM)/(r)}`

where,

M: mass of the moon = 7.3*10^22 kg

G: Cavendish constant = 6.67*10^-11 Nm^2/kg^2

r: distance in between the spacecraft and the center of the Moon =

172 km + 1840 km = 2012 km

Replace the previous values of the parameters into the formula for v and simplify:

Hence, the speed of the spacecraft is approximately 4.91*10^4 m/s