Question

a train is starting from rest and after 10 min it will attain a speed of 140 km/h and then it moving constantly with this speed for next 20 min and after that is retarded its speed up to 80 Km/h and move with this speed for 5 min and then it decreases its speed and finally stop. Make a velocity time graph for its motion​

Answer 1

Answer:

Graph attached

Explanation:

a train is starting from rest and after 10 min it will attain a speed of 140 km/h and then it moving constantly with this speed for next 20 min and after that is retarded its speed up to 80 Km/h and move with this speed for 5 min and then it decreases its speed and finally stop. Make a velocity time graph for its motion​

Initial Speed = 0 km/Hr

at T = 10 min = 1/6 hr Speed = 140 km/Hr

a = (140 - 0)/(1/6)  = 840 km/Hr²

Next 20 min 140 km/Hr

retarded its speed up to 80 Km/h

Assuming retardation = 840 km/Hr²

80 = 140 - 840*T

=> T = 60/840  = 1/14 Hr  = 4.28 min

Then for 5 mins 80 km/Hr

0 = 80 - 840T

=> T = 80/840 = 2/21 hr   = 5.71 min