if a car is falling on a Linear path at a distance d at a constant speed of 30 km per hour then It travel the same distance opposite direction and reached initial position atthe constant speed of 45 km per hour what is the speed of the train
Answers
Considering that there is no car falling and it a train moving to and fro, following discussion holds true.
As the initial speed to cover distance D is 30 km/h, and later it increases to 45 km/h, we can conclude that the time taken by return journey would have been 2/3 of the journey upwards.
i.e. if it took x hours to travel distance D initially at the speed of 30 km/hr, it would need 2*x/3 hours at the speed of 45 km/h.
The average speed would hence be,
= Total distance traveled / total time taken
= 2*D / (x + (2*x/3))
= 6*D/ 5*x
= (6/5) *(D/x)
= (6/5) * (30) { as the distance D is covered in x hour at the speed of 30 km/h)
= 36 km/h
The average speed = ((2*v1*v2)/(v1+v2))
= (2 * 30 * 45) / (30 + 45)
= 2700 / 75
= 36 km/h