Question

A train starts from rest and accelerates uniformly for 30 seconds to acquire a Velocity of 108 km/h. It travels with this velocity for 20 minutes. The driver now applies brakes and the train slows down uniformly to stop after 20 seconds. Find the total distance covered by the train.​

Answer 1

Answer:

30 minutes

Explanation:

a train starts from rest and acceletrates uniformly for 30 seconds to acquire a velocity of 108 km/h.

Answer 2

V = 108km/hr = 30m/s

t1 = 30 second

t2 = 20min = 1200sec

t3 = 20 second

Now, Lets divide the distance in 3 parts

First is distance for accelerating part

2nd is distance for constant velocity part

3rd is distance for retardating part

For first part

v= u + at

30 = 0+ a×30

a = 1m/s^2

2×a× S1 = V^2 - U^2

2×1 × S1 = 30^2 -0

S1 = 450m

For 2nd part

S2 = ut

= 30× 1200= 36000m

For 3rd part

V= u + at

0 = 30+ a×20

a = -30/20 = -1.5

2× a × S3 = V^2 - U^2

2(-1.5) × S3 = 0 - 30^2

S3 = 900/3 = 300m

S = S1+S2+S3

= 450+36000+300 = 36850m