Question

23. A train starts with in 10sec the velocity is 20m/sec and same speed maintain for
more 30 sec. After 5 sec train braked. What is the distance covered by the train. Solve
this question by using Graphical method.
OR​

Answer 1

Answer:

$\huge\bold\red{ANSWER :-}$

===>> The body(train) was moving with a velocity of 20m/s.

the driver must have put on brakes…such that it stops after 10 seconds.

so a deceleration or retardation due to brakes has reduced the speed to zero.

in one sec if the retardation is say a m/s^2 then in 10 sec it will reduce the velocity by 10 times a m/s^2

therefore

==>> 10 s. a m/s^2 = the initial velocity before the breaks was put on = 20 m/s

so a the retardation = 20/10 = 2m/s^2

or one can use kinematical relation

final velocity at time t say v = initial velocity - retardation. time

>>> v(10sec) =0 = 20 m/s - a . 10 s

and one gets to the above result.

However if in another problem an acceleration is happen

$\huge\bold\red{➢}$then v(t) = u (t=0) + a.t