Question

A car starts from rest its acceleration is 2m.s-2 in a straight line. What is it displacement after 10 seconds?

Answer 1

(a/2) t^2

a = 2 m/s^2
t = 10 s
Turn the crank.

Answer 2

1,5m.s-2

Answer 3

Wrong number; wrong dimensions.
1*10^2 = 100 m

What exactly are you doing?