Question

A vehicle travelling with a speed of 18 km/hr comes to a halt in another 10 m travel. Calculate :

(a) its retardation

(b) the time within which it stops.

Answer 1

(a) Here,

u = 18 km/h = 5 m/s

s = 10m

$v^2$ = $u^2$ + 2as

0 = $5^2$ + (2 x a x 10 )

a = -1.25 $m/s^2$

Negative sign shows it is retardation.

(b) a = -1.25 $m/s^2$ , v = 0 , u = 5 m/s

v = u + at

0 = 5 - 1.25 x t

t = 4s