Question

What is phase of SHM? Explain the term phase difference.

Answer 1

 All the particles have the same amplitude and frequency but are at different positions at any given moment. Phase expresses this difference.

Answer 2

Phase is one variable which can be related to all other variables easily (post.  ,velocity   and acceleration).

it means knowing the constants of SHM and the phase would be enough to completely  define SHM.
Phase expresses this difference...

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hope this wll help u...