Question

6.
An express train crosses a person standing on a platform in 20 sec. If its length is
200 m, then find its velocity in kmph.​

Answer 1

Velocity = Distance /Time

= 200×3600/1000×20

= 36kmph

Answer 2

GIVEN:

• Time taken by a train to cross a man = 20 sec
• If the length of the train (Displacement) = 200 m

TO FIND:

• What is the velocity of train ?

SOLUTION:

Let the velocity of the train be 'v' m/s

We know that the formula for finding the velocity of the train is:-

$\large{\boxed{\bf{\star \: VELOCITY = \dfrac{DISPLACEMENT}{TIME} \: \star}}}$

According to question:-

• DISPLACEMENT = 200 m
• TIME TAKEN = 20 seconds

$\sf{\longmapsto v = \cancel\dfrac{200}{20} }$

$\bf{\longmapsto v = 10 \: m/s}$

Change the velocity of the train in km/hr:-

• 1 km = 1000 m
• 1 hr = 3600 sec

$\sf{\longmapsto 10 \times \dfrac{3600}{1000} }$

$\sf{\longmapsto \cancel\dfrac{36000}{1000} }$

$\bf{\longmapsto Velocity = 36 \: km/hr }$

• Velocity = v = 36 km/hr

❝ Hence, the velocity of train is 36 km/hr ❞

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