# Circular motion (1 Viewer)

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#### XodoX

Hey guys, I got the following problem.

Whenever two Apollo astronauts were on the surface of the moon, a third astronaut orbited the moon. Assume the orbit to be circular and 100km above the surface of the moon, where the acceleration due to gravity is 1.52 m/s. The radius of the moon is 1.70 x 106. Determine the astronauts orbital speed and the period of the orbit.
It seems east, btu I still have no idea how to get started on this one

#### The Bob

What equations do you know that could give you a starting point?

The Bob

#### XodoX

None. got all m or T in it, so thatös not gonna work.

#### The Bob

What is the equation Newton's second law in circular motion?

The Bob

#### XodoX

Thats a= v2/r.

You mean v= square root of a * r ? Ok, I didn't think of that then. But what about the period?

#### The Bob

Well that is answered for you in the question:
Assume the orbit to be circular [...]
This enough of a hint?

The Bob

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