Question

A bus is moving with a speed of 54km/hr. Another bus moving at 72km/hr in the same direction tries to overtake it. How much time will the second bus take to completely overtake the first, when it is just behind the first one? Given that lengths of both the buses is 10meters.

• A. 2s
• B. 4s
• C. 4/3 s
• D. 2/3 s

Answer 1

The correct option is B

4s

Speed of bus1 = 15m/s

Speed of bus2 = 20m/s

Relative speed of bus2 with respect to speed of bus1 = 20 - 15 = 5m/s

To overtake, bus2 has to cover a distance of 10m + 10m = 20m

Time taken = $\frac{20}{5}$ = 4s