Username:
   
Password:

I forgot my username or password.

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.

Physics Lessons Review Links Solutions Physics Shop

Velocity is Relative

Relative Motion of 2 Moving Frames

As Jill continues to throw 30mph cookies at Jack, the bus drives by Jack's mom on a bicycle. She is riding 10mph in the same direction as the bus is traveling 25mph.  From her frame of reference, Jack seems to only be going 15mph (25mph - 10mph) and she sees the tossed cookies going 45mph (15mph + 30mph)
 
Relative motion between 2 moving frames in opposite directions

As the cookie tossing between Jack and Jill continues, A car drives by going 40mph in the other direction.  The observer in the car sees Jack going 65mph (40mph + 25mph).  The observer then notices the flying cookies to be traveling a whopping 95 mph! (40mph + 25mph +30mph)
Previous Index