Two buses are running in opposite direction's with the same speed. If length of each bus is 40 metres and they cross each other in 3 seconds, then the speed of each bus is:

Correct option is C

Given:

Two buses are running in opposite directions with the same speed.

Length of each bus = 40 metres

They cross each other in 3 seconds.

Formula Used:​

Speed = $$\frac{\text{Distance}}{\text{Time}}$$​ 

​Solution:

Let the speed of each bus be x km/hr.

Total speed of two buses = x + x = 2x km/hr

Convert units:

1 km = 1000m, so 40 m = $$\frac{40}{1000} = 0.04$$ km. 

1 hour =3600 seconds, so 3 seconds = $$\frac{3}{3600} = \frac{1}{1200}$$ hours 

​Total distance covered

Distance = Length of both buses = 0.04 + 0.04 = 0.08 km

Using the formula: 

$$\\2x = \frac{\text{Distance}}{\text{Time}} \\2x = \frac{0.08 \times 1200}{1} \\\text{Simplify: } \\2x = 0.08 \times 1200 \\2x = 96 \\x = \frac{96}{2} = 48 \, \text{km/hr}$$​