Question

A cyclist driving at 36 kmh⁻¹ stops his motion in 2 s, by the application of brakes. Calculate

1. retardation
2. distance covered during the application of brakes.

Answer 1

Initial velocity = u = 36 kmh⁻¹
= u = `36xx5/18` ms⁻¹ = 10 ms⁻¹
Final velocity = v = 0
Time = t = 2s

(i) Retardation  = a = ?
v = u + at
0 = 10 + a (2)
2a = −10
a = `(-10)/2` = −5 ms⁻²

(ii) Distance covered S =?
v² − u² = 2aS
(0)² − (10)² = 2(−5) S
−10S = −100

S = `100/10`
S = 10 m