Question

A car moving with a speed of $50\, km/hr$, can be stopped by brakes after at least $6 \,m$. If the same car is moving at a speed of $100 \,km/hr$, the minimum stopping distance is

• A. $12\, m$
• B. $18\, m$
• C. $24\, m$
• D. $6\, m$

Answer 1

Answer: (C)

Given, $u =50 km / hr =50 \times \frac{5}{18}=\frac{250}{18} m / s$
$v =0$
$s =6 m \quad$ (at least)
By third equation by motion,
$v ^{2}= u ^{2}+2 as$
$0=\left(\frac{250}{18} \times \frac{250}{18}\right)+2(- a )( s )$
$0=192.90-12 a$
$a =\frac{192.90}{12}=16.07$
Given, $u =50 km / hr =50 \times \frac{5}{18}=\frac{250}{18} m / s$
$v =0$
$s =6 m \quad$ (at least)
By third equation by motion,
$v ^{2}= u ^{2}+2 as$
$0=\left(\frac{250}{18} \times \frac{250}{18}\right)+2(- a )( s )$
$0=192.90-12 a$
$a =\frac{192.90}{12}=16.07$