## College Physics (4th Edition)

a) $1.98\times10^{20}N$ b) The magnitude of the gravitational force that the moon exerts on the earth is the same as that exerted by earth on moon.
a) The distance between earth and moon = r = $3.845\times10^{8}m$ magnitude of gravitational force the earth exerts on the moon = $F=\frac{GMeMm}{r^{2}}=\frac{6.674\times10^{-11}\times 5.974\times 10^{24}\times 7.35\times 10^{22}}{(3.845\times10^{8})^{2}}=1.98\times10^{20}N$ b) As per Newton's third law, the magnitude of gravitational force that the moon exerts on earth is the same as that exerted by earth on the moon.