Question

A train can cross a platform of 100m length in 12 seconds while covers a platform of double of its length in 21 seconds. Find the speed of the train

Answer 1

s= d/t

s=100/12

=8.33333333

Answer 2

Answer:

The speed of the train is 5.55 m/s.

Explanation:

Given that,

Length = 100 m

Time t = 12 sec

Let the length of the train is x.

We need to calculate the length of the train

Using formula of speed

$v=\dfrac{D}{t}$

$v_{t}=\dfrac{100+x}{12}$...(I)

We need to calculate the speed of train when the length of platform is double

Using formula of speed

$v=\dfrac{D}{t}$

$v_{t}=\dfrac{200+x}{21}$....(II)

From equation (I) and (II)

$\dfrac{100+x}{12}=\dfrac{200+x}{21}$

$x = \dfrac{300}{9}$

$x=33.33\ m$

We need to calculate the speed of the train

Put the value of x in equation (I)

$v=\dfrac{100-33.33}{12}$

$v=5.55\ m/s$

Hence, The speed of the train is 5.55 m/s.