A car is moving with a speed of 50kmh- 1 , can be stopped by brakes after at least 6m . If the same car is moving at a speed of 100kmh- 1 the minimum stopping distance is :-

Question

A car is moving with a speed of 50kmh- 1 , can be stopped by brakes after at least 6m . If the same car is moving at a speed of 100kmh- 1 the minimum stopping distance is :- (A) 12m (B) 18m (C) 24m (D) 6m

Tardigrade Admin · Accepted Answer

Stopping distance s=(u2/2 a) s propto u2 (car is same) (s1/ s2)=(u12/u22)⇒ (6/ s2)=((50/100))2=((1/2))2=(1/4) S2=6× 4=24

Q. A car is moving with a speed of $50 km h^{- 1}$ , can be stopped by brakes after at least $6 m$ . If the same car is moving at a speed of $100 km h^{- 1}$ the minimum stopping distance is :-

$12 m$

$18 m$

$24 m$

$6 m$

Stopping distance $s = \frac{u ^{2}}{2 a}$
$s \propto u^{2}$ (car is same)
$\frac{s _{1}}{s _{2}} = \frac{u _{1}^{2}}{u _{2}^{2}} \Rightarrow \frac{6}{s _{2}} = (\frac{50}{100})^{2} = (\frac{1}{2})^{2} = \frac{1}{4}$
$S_{2} = 6 \times 4 = 24$

Q. A car is moving with a speed of 50kmh−1 , can be stopped by brakes after at least 6m . If the same car is moving at a speed of 100kmh−1 the minimum stopping distance is :-

12m

18m

24m

6m