# Time dilation: reference frame [closed]

So I'm calculating how long it will take for half of some muons to decay for in a stationary observers frame of reference. They have a half life of 2.2 * 10^-6 and are moving at a speed of .98c towards earth. I've calculated the gamma factor to be 5.02519. I know that T = Gammafactor * To I've rearanged the equation. Othe people i know are getting different answers from me so I just need to know whether or not i am right since i am unsure at this stage.

## closed as off-topic by ACuriousMind♦, yuggib, Kyle Kanos, Martin, Qmechanic♦May 28 '15 at 23:45

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• See scivee.tv/node/2415 for an extended explanation from the past in glowing black and white... – DJohnM May 28 '15 at 12:05
• By "stationary observer" can we assume you mean one stationary relative to the Earth, not stationary relative to the muons? Also, to see if you're using the equation correctly, are you treating the figure of 2.2 * 10^-6 as being "T" or "To"? – Hypnosifl May 28 '15 at 12:30

You have correctly computed the $\gamma$-factor to be $\gamma=1/\sqrt{1-{0.92}^2}=5.021$
Therefore the lifetime should be $T=\gamma\times T_0=1.105\times10^{-5}$ seconds