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: Atomic Clock Time Dilation Experiment

  1. Jan 7, 2012 #1
    1. The problem statement, all variables and given/known data

    Two atomic clocks are synchronized. One is placed on a satellite which orbits around the earth at high speeds for a whole year. The other is placed in a lab and remains at rest with respect to the earth. You may assume both clocks can measure time accurately to many significant digits.

    a)Will the two clocks stil be synchronized after one year?
    b) imagine the speed of light is much lower than its actual value. How would the results of this experiment change if the speed of light was only twice the average speed of the satellite? Explain your reasoning using a calculation.

    2. Relevant equations

    Δtm = Δts/√(1-v2/c2)

    3. The attempt at a solution

    a) I calculated the Δtm using a theoretical velocity (3x103m/s) and a theoretical Δts 3.1x107 (about how many seconds per year)

    When calculated using Δtm = Δts/√(1-v2/c2) I find no time dilation.. 3.1x107/0.9999999999= 3.1x107

    but the fact that the clocks can go to many significant digits worries me, I think they may not be synchronized after the experiment because of the obvious time dilation that will inevitably take place.. any input here would be awesome!

    b) using the same theoretical #'s, and changing the speed of light of course, I determined much more time dilation would occur as expected, as objects approach the speed of light time dilation becomes very significant.

    =31,000,015.5 s

    significant time dilation as speed becomes closer to speed of light, or in this case speed of light becomes closer to speed of satellite.

    Does everything seem logical and ok?

    Thanks !
  2. jcsd
  3. Jan 7, 2012 #2
  4. Jan 7, 2012 #3
    Average speed of a satellite is about 103m/s in orbit
    Going by this value, we find that γ ≈ 1
    so i don't think there is much difference and that there is any atomic clock that will be able to calculate that ...
  5. Jan 7, 2012 #4
    SO yes, there is time dilation, but it is not detectable even by the most sensitive of atomic clocks?
  6. Jan 7, 2012 #5
    Lets say it is not detectable by nearly all of the atomic clocks we have till now !! :biggrin:
  7. Jan 7, 2012 #6
    ok, thank you very much for your help ! :)
  8. Jan 7, 2012 #7
    What you haven't taken into account is time dilation due to GR. While the clock in orbit will experience time dilation relative to the grounded clock due to the differential velocity, the clock on the ground will experience time dilation relative to the orbiting clock due to the gravitational field.
  9. Jan 7, 2012 #8
    Yes, 103m/s is the velocity of satellite wrt earth
  10. Jan 7, 2012 #9
    Looking at the real world GPS, they actually run faster than clocks on earth. Gravitational time dilation is greater than SR time dilation.


    From wiki:

  11. Aug 6, 2012 #10
    Did they not include this in the question so that you would be able to mention the fact that there is Time dilation that is noticeable between the clocks? Similar to the early experiments with atomic clocks and airplanes?

    I know next to nothing about Physics, just trying to learn myself and that was how I read the question.
  12. Aug 8, 2012 #11
    thats how I interpreted it as well, but I believe I got the question right. I guess its all about how you explain the answer.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook