6.An express train crosses a person standing on a platform in 20 sec.

1.	6.An express train crosses a person standing on a platform in 20 sec. If its length is200 m, then find its velocity in kmph.
Answer» 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 ❞ ______________________