Question

A car travels a distance 100 m with constant acceleration and average velocity of 20 ms^-1. The final velocity acquired by the car is 25 ms^-1.

Find

(i) The initial velocity.

(ii) Acceleration of the car.

Answer 1

Distance travelled s = 100 m

Average velocity V = 20 m/s

Final velocity v = 25 m/s

(i) Let u be the initial velocity.

Average velocity = (Initial velocity + Final velocity)/2

V = (u + v)/2

20 = (u + 25)/2

u = 40 - 25 = 15 m/s^-1

(ii) Let 'a' be the acceleration of the car.

Using the third equation of motion,

v² - u² = 2as

We get,

(25) ² - (15) ² = 2 (a) (100)

625 - 225 = 200 a

a = (400/200) m/s² = 2 m/s^-2