A train comes to a stop in 3 minutes. if the train had a uniform acceleration of -3.5 m/s/s what was initial velocity of the the train?

initial velocity of the train is ##630 ms^-1##

Given the formula of , ##a = (v - u)/t##

So firstly, what we have to do is we have to list down all the known information. Therefore, we should get...

##a = - 3.5ms^-2## ##t = 3 min * 60 s = 180 s## (S.I unit of ##t## is seconds ##s##) ##v = 0 ms^-1## (Because the train stops after the 3 minutes, therefore, its final velocity is zero)

After we list down all the necessary information, substitute the given variables into the formula.

Since ##a = (v - u)/t##, thus,

##-3.5 ms^-2 = (0 ms^-1 -u)/(180s)##

##(0 ms^-1 -u) = -3.5ms^-2 * 180s##

##(0 ms^-1 - u) = -630 ms^-1##

## 0 - u = -630##

## - u = -630 - 0##

## :. u = 630ms^-1##

Therefore, initial velocity of the train is ##630 ms^-1##