Question

A train travels between two stations 'P' and 'Q'. It travels with a velocity 20 km $h^{-1}$ from P to Q and returns to station P with a velocity 30 km $h^{-1}$. The average speed for the total journey.

• A. 25 km $h^{-1}$
• B. 24 km $h^{-1}$
• C. 6.67 m $s^{-1}$
• D. 0 m $s^{-1}$

Answer 1

The correct option is A 25 km $h^{-1}$

Average speed is the ratio of total distance traveled to elapsed time.

Here, from P to Q, it travels distance $20km$ in time one hour and from Q to P, it travels distance $30km$ in time one hour.

So, the average speed of the total journey $=\frac{20+30}{1+1}=25km/h$