0
$\begingroup$

This question already has an answer here:

An object may be regarded to be at rest or in motion depending on the frame of reference chosen to view the object. Because of length contraction it would mean that the same rod may have two different lengths depending upon the state of the observer. Is it true?

Also, Mass of a particle depends on its speed. Does the attraction of the Earth on the particle also depend on the particle's speed?

$\endgroup$

marked as duplicate by John Rennie special-relativity Jul 3 at 7:30

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.