Question

An object accelerates uniformly from rest and covers 8m in 2 seconds. What is the distance covered in the third second?

Answer 1

X(t)= (a/2) t^2
8 = (a/2)*2^2 = 2a
a = 4 m/s^2

After 3 seconds, the distance travelled from the starting point is
X(3) = 2*3^2 = 18 m
18 - 8 = 10 m was covered in the third second.
First second: deltaX = X(1) = 2 m
Second second: deltaX = X(2)-X(1) = 6 m
Third second: deltaX= X(3)-X(2) = 10 m