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Question
A motorbike, initially at rest, picks up a velocity of 72 kmh−1 over a distance of 40 m. Calculate
- acceleration
- time in which it picks up above velocity.
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Solution
Initial velocity = u = 0
Final velocity = v = 72 km/h = `72xx5/18` m/s
v = 20 m/s
Distance = S = 40 m
(i) v2 − u2 = 2aS
(20)2 − (0)2 = 2a (40)
80a = 400
a = `400/80`
a = 5 ms−2
(ii) v = u + at
20 = 0 + 5t
5t = 20
t = `20/5`
t = 4 s
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