# B Velocity dialation

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1. Aug 23, 2016

### AleksanderPhy

Hello I have a question about how time effects velocity:So we have a car on earth traveling 200m with 5 seconds we get that car moves 40m/s and 40x3600=144000 and 144000:1000=144km/h so car on earth travels 144km/h now let's consider a that there is observer on spacecraft traveling 0.5c through time dialation formula:t=1/√1-v/c we get that observer on spacecraft get's that car travels 200m with 0.5 seconds so observer thinks that car goes 1440 km/h. Does this mean that time effects velocity?

2. Aug 23, 2016

### GeorgeDishman

There's a mistake in your formula, it should be 1/√(1-(v/c)2). You also need to include the effect of length contraction but from the point of view of the spacecraft, the car is travelling at roughly 0.5c (at little more or a little less depending on the directions).

Velocity Addition Formula

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