If you were riding the particle, you certainly would see the Earth accelerate. Otherwise, how would it go from not moving at all relative to you to moving very fast relative to you?
Originally Posted by Squashed
In general, you can determine what portion of the total energy is kinetic energy and what portion is rest energy from just the velocity (relative to you). If you also know the total energy (relative to you), you can work out the rest energy, and it will always be the same, regardless of how the object is moving relative to you.
Last edited by Grey; 2006-May-26 at 06:43 PM.
Conserve energy. Commute with the Hamiltonian.