A train 125 m long passes a man running at 5 km/hr in the same direction in which the train is going in 10 seconds. The speed of the train is:
45 km/hr
50 km/hr
54 km/hr
55 km/hr
Explanation:
| Speed of the train relative to man =$ \left(\dfrac{125}{10} \right) $m/sec |
| =$ \left(\dfrac{25}{2} \right) $m/sec. |
| =$ \left(\dfrac{25}{2} \times\dfrac{18}{5} \right) $km/hr |
= 45 km/hr.
Let the speed of the train be $ x $ km/hr. Then, relative speed = $\left( x - 5\right)$ km/hr.
$\therefore x $ - 5 = 45 $\Rightarrow$ $ x $ = 50 km/hr.