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An introduction to Relativistic Mechanics 

            The purpose of this page is to  give a brief introduction of relatavistic mechanics to people who plan to pursue physics at a more advanced level, in their future studies.

            At a high school level almost all of the physics being taught is Newtonain physics. Newtonian physics is sufficient for day to day life but there are times when the answers that Newtonian physics will give us are not correct. An excellent example of the is when adding vectors on a straight plane. If one were hypothetically travelling at 1.0 X 10⁸ m/s and were to shine a flashlight ahead of him (the speed of light  through a vacuum is 3.0 X  10⁸ m/s) then the relative speed of light in comparison to the ground would be 4.0 X 10⁸ m/s if calculated using Newtonian theory. The problem with this answer is that the  speed of light is always measured as 3.0 X 10⁸ m/s regardless of the velocity of the observer or the source of the light itself. It is probably now apparent that a new theory was needed to calculate the answeers for questions (as abstract as they may be) for questions such as this.

          An answer to these problems was found in the "theory of relativity" which was published in 1905 by Albert Einstein at the comparatively young age of 26. His theories and formulas gave us answers to questions such as the one above as well as revolutionizing and changing the world of physics as we know it. In his theeory it is believed that Newtonian physics is reliable just for special cases (although these cases are for the most part the only cases that are encountered by the general populace). His theory encompassed Newton's and at the same time expanded into areas that were until that point unanswerable.

        In this page what will be covered will be relativistic formulas for determining relative velocities on a single plane (same direction), length contraction, the mass increase of an object as acceleration of an object increases and time dilation. There will also be a small explanation for Einstein's mass-energy equivalency formula E = mc². On all pages there will also be sample questions as well as practice questions  (of which the answers will be provided).

For all of the equations in the following pages the speed of light = c = 3.0 X 10⁸ m/s,  v = velocity and will always be measured in m/s, t = time and will be measured in s and d or L = length and will be measured in m. Incidentally exponential notation is used as opposed to square root symbols (for typing convenience). I cannot stress the importance of "BEDMAS"  enough.

Return in Spring 2001 and try out some actual relativistic questions (with solutions!)