A car travels a distance 100 m with a constant acceleration and average velocity of 20 m s-1. The final velocity acquired by the car is 25 m s-1. Find: (i) the initial velocity and (ii) acceleration of car.

(i) Given, v = 25 m s^-1

As we know,

Average velocity = u+v\over 2 = 20 m s^-1

Substituting the value we get,

u+25\over 2 = 20

or, u +25 = 20 × 2 =40

or, u = 40 – 25 = 15 ms^-1

Hence, initial velocity of the car is 15 m s^-1

(ii) We know, from the equation,

v² = u² + 2aS

S = 100 m

v = 25 m s^-1

u = 15 m s^-1

Substituting the values in the formula above we get,

25² = 15² + (2 × a × 100)

or, 625 = 225 + 200 a

or, 200 a = 625 – 225

or, a = 400 / 200 = 2 m s^-2

Hence, acceleration of car = 2 m s^-2