Kinematics Question 353
Question: Three elephants A, B and C are moving along a straight line with constant speed in same direction . Speed of a is $ 5m/s $ and speed of c is 10 m/s. Initially separation between A and b is ’d’ and between B and c is also. When ‘B’ catches ‘C’ separation between A and C becomes 3d. Then the speed of B will be
Options:
A) $ 7.5m/s $
B) $ 15m/s $
C) $ \text{20 }m/s $
D) $ \text{5 }m/s $
Show Answer
Answer:
Correct Answer: B
Solution:
B catches C in time t then $ \text{t=}\frac{d}{u-10} $ . Separation by this time has increased by ’d’ between A and C hence $ ( 10-5 )\times \frac{d}{( u-10 )}=d,u=15m/s $
