Question

a car moving at a rate of 18km/h .when the brakes were applied , it comes to rest in a distance of 100m. calculate the retardation produced by the brakes

Answer 1

By newton's equation of motion
v^2-u^2=2as
So,here v=0
u=5m/s
s=100
0-25=2*100*a
a=-8m/s^2

Answer 2

$\sf{\underline{\underline{Given}}}$:

$\sf{v = 0}$

$\sf{u = 18 \: km/h\:=\:5 \: m/s}$

$\sf{S = 100 \: m}$


$\sf{\underline{\underline{Using\:the\:equation\:of \:motion}}}$:

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


$\sf{\underline{\underline{So}}}$:

Substituting the values in the above formula,

$\sf{\underline{\underline{We\: get,}}}$

$\sf{a = \frac{ - 5 \times 5}{2 \times 100}}$

$\sf{a = \frac{ - 25}{200} }$

$\sf{a = - \frac{1}{8}}$

$\boxed{a = - 0.125 \: {m/s}^{2}}$


$\sf{\underline{\underline{So}}}$:

The retardation produced by the brakes is $\boxed{0.125 \: {m/s}^{2}}$