Question

A train can cross a platform of equal length in 5 minutes. It can cross a man running in the direction of the train with the speed of 2m/s in 7 minutes. Find the speed of the train(in km/h).​

Answer 1

Question :-

A train can cross a platform of equal length in 5 minutes. It can cross a man running in the direction of the train with the speed of 2m/s in 7 minutes. Find the speed of the train(in km/h) ??

Given :-

• length :- 5m
• speed :- 2m/s 7 minutes

To find :-

• the speed of the train in km/h

Solution :-

let the length of the length of train be :- l meter

and the speed of the train be : - s m/s

now according to questions :-

$\longrightarrow \sf \: 2l = s \times 5 \times 60 \\ \\ \\ \longrightarrow \sf \: l = 150s - - - - (1) \\ \\ \\ \longrightarrow \sf \: l = (s - 2) \times 7 \times 60 \\ \\ \\ \longrightarrow \sf \: 270s = 840$

$\longrightarrow \sf \: s = \cancel \frac{840}{270} \\ \\ \\ \longrightarrow \sf \: s = 3.11ms \\ \\ \\ \longrightarrow \sf \: s = 3.11 \times \cancel \frac{18}{5} = 112.k m \:$

∴ the speed of the train is 112.km