Question

a 260m long train crosses a platform thrice its length in 80 s. what is the speed of the train in km/h?

Answer 1

Length of the train = 260m

length of platform=(3*260) = 780m

Total length = 260+780=1024m

speed=distance/time

therefore, s=1024/80 =13m/s

In Km/hr= 13*18/5 = 234/5

= 46.8km/hr

Hope this will help you dear.

Answer 2

Given :

Length of train , l = 260 m = 0.26 km .

Time taken to cover a distance of thrice the length of train is :

$t=80 \ s=\dfrac{80}{60\times 60}\ hr$ .

To Find :

The speed of the train in km/h .

Solution :

We know , distance travelled is given by :

$d=3\times l=3\times 0.26 = 0.78\ km$ .

We know , velocity is given by :

$v=\dfrac{d}{t}\\\\v=\dfrac{0.78}{\dfrac{80}{60\times 60}}\\\\\\v=\dfrac{0.78\times 60\times 60}{80}\\\\v=35.1\ km/h$

Therefore , the speed of the train is 35.1 km/h .

Learn More :

Speed and velocity

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