How Does Time Dilation Influence Perceived Velocity?

[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 dilation 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?

 

[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 traveling at roughly 0.5c (at little more or a little less depending on the directions).

Velocity Addition Formula