Question

a car moving with velocity 54 km per hour on a straight road stops on applying brakes after covering a distance of 20 m compute the acceleration of the car . tell it step by step

Answer 1

v= 54 km/hr or 15 m/s
s = 20m
so,

$v {}^{2} \: - \: u {}^{2} = \: 2as$

$0 - 15 {}^{2} = 2 \: . - a \: \: \: . \: 20$
a is negative as the body is regarding and velocity is decreasing.
so,

$- 225 = - 40 \times a \\ 225 \div 40 = a$
$a = 5.625 \: ms {}^{ - 2}$