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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.
Solution
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
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