Question

A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively.What is the speed of the train?.

Answer 1

Let the length of train be $x$ meters and speed be $y$ m/sec.

Then $\frac{x}{y}=8\Rightarrow x=8y$

Now $\frac{x+264}{20}=y\Rightarrow 8y+264=20y\Rightarrow 12y=264$

$y=22$

Speed $=22$ m/sec. $(22\times \frac{18}{5})$ km/hr $=79.2$ km/hr.