Question

avell the collision.
8. On a 200 km track, a train travels the
first 50 km at a uniform speed of 40 km/h.
How fast must the train travel for the
next 150 km in order to maintain the
average speed of 60 km/h for the entire
journey?​

Answer 1

Explanation:

total distance =200km

1st 50km speed = 40km/h

average speed =60 km/h

time used to cover 1st 50km= d/v

=50/40 hr

total time for journey =d/v

=200/60 hr

remaining time =(200/60)-(50/40)

=(800-300)/240

=500/240

=25/12

speed of train for 150 km= d/t

=150/(25/12)

=(150*12)/25

=6*12

=72 km/h

Answer 2

$\sf \pmb{Answer :}$

time =200/60=20/6

average speed=Total distance/Total time

Time taken 50km=5/4

remaining time=20/6-5/4=25/12

speed=distance/time

150*12/25=72

remaining speed=72km/h