question archive An intergalactic spaceship arrives at a distant planet that rotates on its axis with a period of T = 37 hours
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An intergalactic spaceship arrives at a distant planet that rotates on its axis with a period of T = 37 hours. The spaceship enters a geosynchronous orbit at a distance of R = 5.7 • 108 m.
From the given information, write an equation for the mass of the planet.
Calculate the mass of the planet in kilograms.
For geosynchronous orbit Centripetal Force is equal to Gravitational Force
Gravitational Force = Centripetal Force
GMm/R2 = mv2 / R
GM/R = v2
we know that
time period T = time taken to complete a cycle around M so
T = 2πR/v
v =2πR/T put this v value above
GM/R = v2 = (2πR/T )^2
GM /R = 4π2R2 /T2
from here
M = 4π2R3 /T2G
now just plug the values
T = 37 *60*60 = 133200 sec
R = 5.7*10^8 m
M =
kg answer