A plane travels 5.1 102 m while being accelerated uniformly from rest at the rate of 4.9 m/s2. What final velocity does it attain?

I assume that the distance you were trying to write is D = 510 m. You should have written it as 5.1*10^2 m

The acceleration rate is a = 4.9 m/s^2

Vmax = sqrt(2a*D) = 70.7 m/s
= 254.5 km/h
= 158 mph