Q. Two cars are moving in the same direction with a speed of $30kmh^{- 1}$. They are separated from each other by 5 km. Third car moving in the opposite direction meets the two cars after an interval of 4 min. What is the speed of the third car?
A) 30 $kmh^{- 1}$
B) 35 $kmh^{- 1}$
C) 40 $kmh^{- 1}$
D) 45 $kmh^{- 1}$
Explanation
(d) This problem can be solved by using the concept of relative velocity
$v + 30 = 75$
or $v = 45kmh^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.