Question

Two trains A and B which are 100 km
apart are travelling towards each other on
different tracks with each having an initial
speed of 50 km/h. The train A accelerates
at 20 km/h2 and the train B retards at the
rate 20 km/h2. The distance covered by
the train A when they cross each other is:​

Answer 1

Explanation:

Suppose , the train A and B meet at a common point A after time t

from the start .

Common initial velocity is 50 km/h.

Distance travelled by A is, S

A

=x

Distance travelled by is Bis ,S

B

=100−x

Now, A is accelerating with

h

2

20km

So,using equation:

S

A

=ut+

2

1

at

2

x=50t+

2

1

20t

2

=50t+10t

2

and B is retarding with

h

2

20km

So using equation

S

B

=ut+

2

1

at

2

100−x=50t−10t

2

i.e. adding both equation

100=100t

t=1h

Distance travelled by A = 50t+10t

2

=50+10=60km

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