CK-12 Foundation
Ck 12: Episd: Inertial Frames and Relative Motion
[Free Registration/Login may be required to access all resource tools.] Relative motion is always measured with a frame of reference. Evaluate a variety of frames of reference and inertial frames to understand relative motion.
University of St. Andrews (UK)
University of St. Andrews: Special Relativity
A historical approach to special relativity, giving all the events and names in the history of discovery of special relativity. Many links to these individuals.