Opted Physics #12

[Gainesvillian]

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Does anyone remember how they solved opted physics #12?

A satellite of mass 200kg completes a circular orbit of the Earth in 120 minutes. A 400kg satellite is then put into orbit at the same ht above Earth. Which of the following represents the time, in minutes, for the 400kg satellite to complete a circular orbit?

A.60
B.120
C.180
D.240
E.360

Opted says 120.

 

[Framecontrol]

hey dude,

I was wondering about this one too. It seems as though mass is not a issue when calculating the anwser...

what formula though??

 

[Gainesvillian]

yea idk im wondering if its just conservation of energy. same potential energy because same height would mean same kinetic energy. Same velocity for the same distance=same time?

 

[blysssful]

centripetal acceleration:
a= v2/r
and it only causes a change in the direction of the motion, so the magnitude of velocity (and therefore time it takes to complete the orbit) are the same.