Question

A motorbike, initially at rest, picks up a velocity of 72 kmh⁻¹ over a distance of 40 m. Calculate

1. acceleration
2. time in which it picks up above velocity.

Answer 1

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