Question

Two cars are moving in the same direction with the same speed of $30km/hr$. They are separated by $5km$. What is the speed of car moving in the opposite direction if it meets the two cars at an interval of $4$ minute:

• A. $45km/hr$
• B. $60km/hr$
• C. $105km/hr$
• D. None

Answer 1

The correct option is A $45km/hr$

Since the two cars are moving in the same direction with same speed therefore relative speed between two cars is zero.

Let the relative speed of the third car be w.r.t the two cars.

Relative velocity of the third car: $\frac{5km}{\left(4/60\right)h}=75km/h$

Actual velocity of the third car:$75-30=45km/h$