1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: A question about special relativity, Please Help

  1. Jun 2, 2009 #1
    Hello everyone,

    This is not a typical homework question. I found this confuses me when my teacher derives the special relativity formula in the class. Here is the derivation:

    1. The astronaut, stationary relative to the clock incorporated in the bottom mirror, measures a time interval 2 delta t(s) for the light to make a round trip and so infers delta t(s) to be the duration of the upward journey.

    2. The time interval as measured by an observer on Earth, who records it as delta t(m).

    3.The path of the light forms two identical right triangles

    So, the textbook and my teacher use the Pythagorean theorem to make a equation, and isolate delta t(m). Since the scenario was testing with the path of light, therefore the formula would include c square, of course.

    Now, my question is: Can we use this formula for the other problems that are testing with the path of things other than light, such as a ball. If we can, should not we replace the speed of light with the speed of the ball?

    I did talk to my teacher about it, but he could not find any answers yet, so I guess I may get some help here.

    Sorry about my grammar. I hope I state my question clear.

    Thanks to anyone who are trying to help!
  2. jcsd
  3. Jun 2, 2009 #2
    Hi there,

    From your explanations, you are explaining time dilation. The two right triangles that your teacher was using comes from the postulate that light always travels at the speed of light, otherwise it could be considered as a boucing ball.

    Now, if I understand your question correctly, the path of a tennis ball bouncing vertically in a train passing by, would look like it's travelling in a triangle shape path for you standing still next to the train. If this is what you meant, then you can replace light photons with any object you feel like.

  4. Jun 2, 2009 #3
    Thank you fatra2 for reply my question.

    looking forward to see more explanations.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook