Question

The Sangrur Express train is $800$ metres long. It crosses a tunnel in $1$ minute while running at a speed of $78km/hr$. What is the length of the tunnel?

• A. $260m$
• B. $440m$
• C. $500m$
• D. $352m$

Answer 1

The correct option is C $500m$

Let length of tunnel is $x$ meter

Distance = $800+x$ meter

Time $=1minute=60seconds$

Speed $=78km/hr=78\times \frac{5}{18}m/s=\frac{65}{3}m/s$

$Distance=Speed\times Time$

$\Rightarrow$ $800+x=\frac{65}{3}\times 60$

$\Rightarrow$ $800+x=1300$

$\therefore$ $x=1300-800=500m$