Laws Of Motion Question 246
Question: An automobile travelling with a speed of $ 60km/h, $ can brake to stop within a distance of 20 m. If the car is going twice as fast, i.e. 120 km/h, the stopping distance will be [AIEEE 2004]
Options:
A) 20 m
B) 40 m
C) 60 m
D) 80 m
Show Answer
Answer:
Correct Answer: D
Solution:
The stopping distance, $ S\propto u^{2} $
$ (\because \ v^{2}=u^{2}-2as) $
therefore $ \frac{S _{2}}{S _{1}}={{( \frac{u _{2}}{u _{1}} )}^{2}}={{( \frac{120}{60} )}^{2}}=4 $
therefore $ S_2=4\times S_1=4\times 20=80m $
