Question

A train is travelling at a speed of 90 km/h brakes are applied so as to produce a uniform acceleration of -0.5 m s-2. Find how far the train will go before it is brought to rest .

Answer 1

First find the time after which the train stops.
v=v₀-a*t=0, where v₀=90 km/h=90/3,6 m/s = 25m/s - initial velocity
v=0 the velocity when the train stops
t - time

Hence t=v₀/a=50 s
in that formula we take the module of a

The distance travelled s=v₀*t-a*sqr(t)/2
after substituting the value of t to the last formula we'll get the value of distance
s=625 m