Question

How long is a train which passes a signal in twenty seconds at a speed of 108 km/h

Answer 1

The length of the train is
`600\ m`

Explanation:

we know that

The speed is equal to the ratio of the distance by the time

Let

d -------> the distance in meters

t ------> the time in seconds

s -----> the speed in m/sec

`s=(d)/(t)`

Remember that

1 km=1,000 m

1 h=3,600 sec

we have

`s=108(km)/(h)`

Convert to m/sec

`s=108((1,000))/(3,600)=30(m)/(sec)`

Find the length of the train

we have

`s=30(m)/(sec)`

`t=20\ sec`

substitute in the formula and solve for d

`30=(d)/(20)`

`d=30(20)=600\ m`