What is the distance travelled by a ball that starts at 2 m/s and moves with an acceleration 4 m/s^2 to reach 18 m/s.

Acceleration is the rate of change of speed. For a body
travelling at a speed u, the speed after time t is given by u + at where a is the rate
of acceleration. Now the distance travelled by  the body is the average of the initial
speed  and the final speed multiplied by the time
travelled.

Here final speed is 18. Now as acceleration is
4,

18 = 2 + 4t

= > t =
4.

Therefore the time taken is 4
sec.

So the distance travelled is given as 4*(2+ 18)/2 = 4*
10 = 40 meters.

The required distance
travelled is 40 m.