Question

A train starts from rest and accelerates uniformly for 30 s to acquire a velocity of 108 km/hr. It travels with this velocity for 20 min. The driver now applies brakes and the train retards uniformly to stop after 20 s. Find the total distance covered by the train.

Answer 1

This question can be solved by v-t graph.

if you have any other doubts, don't hesitate to ask.

regards,
nimit sharma

Answer 2

Answer:

$36750 \: m$

Explanation:

When the train starts from rest,

u= 0,

t= 30s,

v= 108 km/h = 108 × 5/18 = 30 m/s.

Now,

a= v-u/t = 1 m/s².

Distance ,S1 = ut + 1/2 at²

= 0 + 1/2 × 1 × 30 × 30

= 450 m.

At uniform velocity of 30 m/s for 20 min, i.e., 1200s,

Distance, S2 = 30 × 1200 = 36000 m.

Now,

On applying brakes,

t= 20s,

u= 30 m/s,

v= 0.

a= v-u/t = 0-30/20 = -1.5 m/s²

Distance S3 = v² - u²/2a

= 0 - (30)² /2 × 1.5

= 300 m

Therefore,

The total distance traversed = S1 + S2 + S3

= (450 + 36000 + 300) m

= 36750 m