Question

a moving train is brought to rest within 20 seconds by applying brakes. find the initial velocity, if the retardation due to brakes is 2m/s2 ​

Answer 1

using the equation of motion

v=u+at

0=u+2*20

-u=40

u=-40m/s

Answer 2

Answer:

40m/s

Explanation:

since a= -2m/s2( negative sign because the train is slowing or retarding down),  time=20seconds and final velocity v=0m/s

Hence, applying the 1st equation of motion, we get

v = u + at

=>0 = u + (-2)20

=>0 = u - 40

=>u = 40m/s