Question

A body with an initial velocity of 18 km h–1 accelerates uniformly at the rate of 9 cm s–2 over a distance of 200 m. Calculate :
(i) the acceleration in ms–2
(ii) the final velocity in ms–1

Answer 1

Acceleration = 0.09 m/s²

Final velocity = 7.81 m/s

Explanation:

Given initial velocity u = 18 km/hr = 18 * 1000 / (60 * 60) m/s

acceleration = 9 cm/s^2  

distance of 200 m.

 

(i) Acceleration is given in cm per second square. To convert:

9 cm / s^2 = 9/100 m/s^2 = 0.09 m/s^2

(ii) the final velocity v in ms–1

u = 18 km / hr = 18 * 1000 / (60 * 60) m/s = 5 ms–1

a =  0.09 m/s²

s = 200 m

v² = u² + 2as

v² = 5² + 2 * 0.09 * 200

v² = 25 + 36

v² = 61

v = √61 = 7.81 m/s