Question

On a track of length 100km,the train covers first 30 km with a constant speed of 30km/h what sho be the speed of the train for the next 70km so that the average speed remains 50km/h for the entire trip

Answer 1

By definition of average velocity we know that

v(avg) = total displacement/ total time

so 50= 100/t

hence t= 2 hr

FOR THE 1ST PHASE:

t1 = x1/ v1

so t1 = 30/30= 1 hr

FOR THE 2ND PHASE:

the train had to cover 70km in 1hour since total time is 2hour

hence it has to travel with a constant velocity of 70km/hr