Q. 404.3( 16 Votes )

A train travels the first 15km at a uniform speed of 30 km/h; the next 75 km at a uniform speed of 50 km/h; and the last 10 km at a uniform speed of 20 km/h. Calculate the average speed for the entire train journey.

Answer :


(a) For the first part
In the first part, the train travels 15 km at a speed of 30 km h-1
 The speed of the train is given by
We know the speed of train =30 km/h
              The distance travelled by tain= 15 km 


Time taken by train in the first part, T1=15/30=0.5 h

(b) For the second part
The distance, D= 75 km
The speed, S=50 km/h
Putting the values in the formula to calculate time taken
Time taken, T2=75/50=1.5 h

(c) for the third part
The distance, D=10 km
The speed, S=20 km/h
Putting the values in the formula to calculate time taken
Time taken by train, T3=10/20=0.5 h.


Total distance travelled by train= 15 +75+10 =100 km
Total time taken by train=T1+T2+T3 =0.5 +1.5+0.5=2.5 h

Putting the values in the above formula, we get
Average speed, S=100/2.5=40 km h-1 
 



Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
About Acceleration50 mins
Velocity Time GraphFREE Class
Champ Quiz | Motion under gravity46 mins
Second Equation of Motion48 mins
Understanding Motion60 mins
Interactive Quiz - Motion29 mins
Learn The Use of Equations of Motion37 mins
Learning Second Equation of motion41 mins
Third Equation of Motion36 mins
NCERT | Motion - Part 153 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses
RELATED QUESTIONS :