Question

A train travels 700 meters in 35 seconds. What is its speed in km $h^{-1}$ ?

Answer 1

Given: A train travels 700 meter in 35 seconds.
We need to calculate speed in km $h^{-1}$
Distance $=700$ meter
$=700\times \frac{1}{1000}km$

$=\frac{7}{10}km$ $[1km=1000m,1m=\frac{1}{1000}km]$

Time $=35$ second

$=35\times \frac{1}{60}minute[1min=60seconds$
$\Rightarrow 1sec=\frac{1}{60}minute]$
$=35\times \frac{1}{60}\times \frac{1}{60}hour[1hour=60min$
$\Rightarrow 1min=\frac{1}{60}hour]$
$=\frac{35}{3600}$

$\because Speed=\frac{distance}{Time}$

$=\frac{\frac{7}{10}}{\frac{35}{3600}}km/h$
$=72km/h$
Hence, the speed of the train is 72 km/h.