# physics - special relativity

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When a rocket is moving at a constant speed, it has a relativistic mass that is 60 percent greater than its rest mass.

Find the speed of the rocket.

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So far, I tried using the relativistic mass equation..

0.6m = mv / square root 1-(v/c)2

• physics - special relativity -

what did you get when you used that formula??

• physics - special relativity -

whoops..
wrote it wrong.. should be..

0.6m = (mv) / (square root 1 - (v/c)^2)

and that's as far as i got.. i don't know what to do from there or if it's the right equation :S

• physics - special relativity -

The relativistic mass is 1.6 times the rest mass. The rest mass cancels out.

1.6 = 1/sqrt[1 - (v/c)^2]
sqrt[1 - (v/c)^2] = 5/8
1 - (v/c)^2 = (5/8)^2 = 25/64
(v/c)^2 = 39/64
v/c = 0.781

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