Question

how many seconds will a 500 meter long train moving with a speed of 63 km/hr, take to cross a man walking with a speed of 3 km/hr in the direction of the train? a.42

Answer 1

Given,

Speed of train = 63km/hr.

Speed of man = 3km/hr

Now, Since  both objects are moving, so we need to find  relative  speed . Relative  speed   of train   with respect to  man will be  treated as  the only  one of  them object  is  moving  in direction of  train. Moreover Relative  veolocity   can also be  explained  as  man is  in  rest while  train is  moving.

Relative  velocity of  train with respect  to man = 63 - 6 = 60 km/hr = 50/3 meter per/second

Now,

Train   have  to  travel 500 meter distance  with respect  to man

Hence,

Time taken to cross the man = distance/speed

                                                = 500/(50/3)

                                                = (500*3)/50

                                               = 30 seconds