Acceleration of a body is defined as the rate of change of velocity of the body with respect to time. Note: Acceleration is the measure of change in velocity of the body per unit time. It is a vector quantity. Acceleration is positive if the velocity of the body increases with time and is negative if the velocity of the body decreases with time.

A bus starting from rest moves with a uniform acceleration of 0 . 5 m s 2 for 4 minutes. Find the speed acquired.

Given, Acceleration, a = 0 . 5 m s - 2 . Time, t = 4 min = 4 × 60 s = 240 s . Initial velocity, u = 0 . Substituting the values in the first equation of motion which is v = u + a t we get, The final velocity, v = 0 + 0 . 5 × 240 = 0 . 5 × 240 = 120 m s - 1 . Thus, the speed acquired by the bus is 120 m s - 1 .