Question

a train moving at 72 kmph is brought to rest in 10 seconds. find the distance covered by it in this time.

Answer 1

Since, the train is moving then its Final Velocity becomes Zero.

Convert Km/h to m/s

=> 72 Km/h = (72 x 5/18) m/s = 20 m/s

Now,

Initial Velocity = 20 m/s

Time = 10 s

In this question we have to find at first Acceleration then with the help of that Acceleration we will find distance covered.

=> v = u + at

=> 0 = 20 + a x 10

=> -20 m/s = 10a

=> a = -20/10 m/s^2

=> a = -2 m/s^2

Hence, -ve signs shows de-acceleration.

Now,


=> v^2-u^2 = 2aS

=> 0^2 - 20^2 = 2 x -2 x S

=> -400 = -4 x S [ Here, both -ve signs cancel eachother ].


=> 400/4 = S

=> S = 100 m


As we also know that Distance can't be measured in negative.


So, the Distance Transversed after applying brake = S = 100 m