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In support of all the students who are displaced from school due to the Corona virus. Access to physics zone and chemistry zone lessons are now available free of charge. This will be maintained at least through August 1st 2020. Learn and be well.

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Velocity is Relative (Uncle Velocity?)

Velocity is not absolute, it is dependant on the observer.  That is why we say it is "relative" to the observer's state of motion

Reference Frame of Bus

Take the example of Jack and Jill sitting in a room.  Jill sees Jack at rest and Jack sees Jill the same way.  It is only when we "zoom out" on our point of view that we discover that Jack and Jill are on a bus moving with a constant velocity (same amount and direction).  Jack and Jill are looking at each other from the reference frame of the bus.
 
Stationary Reference Frame

Jill's Mother, waiting for her own bus, sees Jill's bus go by at 25mph.  She sees Jill traveling 25mph.  Jack on the other hand, sees Jill going zero mph.  What they observe seems to depend on their state of motion (frame of reference).
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