Question

Answer each of the following questions in one paragraph. If you want/need, you can supplement your written explanation with diagrams or equations.

1. Provide an example of an inertial frame of reference and a non-inertial frame of reference. Explain the difference.

2. Using the Michelson-Morley experiment as an example, explain why classical mechanics was unable to explain natural phenomena.

3. Using at least one of Einstein's "thought-experiments", explain how special relativity addresses how it is possible for observers in two different inertial reference frames to “disagree” about time and distance intervals.

4. Describe how special relativity explains the conditions under which classical mechanics breaks down.(When would you, as an observer begin to notice the effects of time dilation and length contraction?)

5. In the early 20th century, the law of conservation of mass was replaced by the law of conservation of mass-energy. Why was this change needed, and how does E=mc² relate to the special theory of relativity?

Answer 1

(1) An Inertial frame of reference is one, where the frame is not accelerating, ie. it is at constant velocity (it can be 0), whereas non-inertial frame is one where the frame itself is accelerating. To explain physics in non inertial frames we have to bring in the concept of Pseudo Forces which is a force which is not there actually, but is arising due to the accelerating frame, this is not required in an inertial frame and laws of physics are valid without any pseudo forces. A car moving at a constant speed is an example of inertial frame of reference whereas, a merry go round is an example of non inertial frame of reference.