# Remote Frames of ref

## Main Question or Discussion Point

lest say you have a man on the moon and one on mars. For them to be in the same frame of ref the only parameters that needs to be common to both is that they must both be travelling at the same velocity and in the same direction yes?

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JesseM
lest say you have a man on the moon and one on mars. For them to be in the same frame of ref the only parameters that needs to be common to both is that they must both be travelling at the same velocity and in the same direction yes?
Yes, a frame of reference is just a coordinate system that can be used for events anywhere in space, so if you choose a frame where the man on the moon has a position coordinate that's not changing over time, and the man on mars is at rest relative to the man on the moon, then the position coordinate of the man on mars won't change over time in this frame either, so this frame is the rest frame for both of them.

thank you Jesse for your prompt reply...that was very prompt :) are you Australian ?

JesseM
thank you Jesse for your prompt reply...that was very prompt :) are you Australian ?
No, just up too late! :) It's 3:45 AM now here, I guess I should get to sleep...

you are answering physics questions at 3.45 am thats just a tad freaky :)

clem
lest say you have a man on the moon and one on mars. For them to be in the same frame of ref the only parameters that needs to be common to both is that they must both be travelling at the same velocity and in the same direction yes?
Their "frame of reference" does not depend on their velocities.
They are in the same frame of reference if the same axes are used for each, independently of what they are doing.

JesseM
Their "frame of reference" does not depend on their velocities.
They are in the same frame of reference if the same axes are used for each, independently of what they are doing.
I think rab99 was asking whether they share the same rest frame, which does of course depend on their velocities.

lest say you have a man on the moon and one on mars. For them to be in the same frame of ref the only parameters that needs to be common to both is that they must both be travelling at the same velocity and in the same direction yes?
Clearly a man on the Moon and one on Mars are definitly not in the same frame of reference.

Two objects are only in the same frame of reference if neither accelerates and that the distance between them remains constant.

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Helo all.

Perhaps there is some confusion here between "frame of reference" and "rest frame"?

Matheinste.