Question

find the initial velocity of train which stopped in 25sec. The retardation produced in the train is 1.5m/s

Answer 1

Let initial velocity=u
The final velocity (v)=0 (as it comes to rest)
Acceleration (a)= –1.5m/s. (as it is retarding)

By the 1st equation of motion,
v=u+at
u=v – at
= 0– (–1.5)×25
=0+37.5
so u=37.5m/s.

Thus initial velocity is 37.5m/s.

HOPE IT HELPS.....

Answer 2

initial velocity(u) = ?
final velocity(v) = 0
retardation(a) = -1.5m/s
time taken(t) = 25s

retardation/negative acceleration =
initial velocity - final velocity / time taken

a = v - u / t
-1.5m/s^ = 0 - v / 25s
-1.5 = -v / 25
-v = -1.5 * 25
-v = - 37.5m/s
v = 37.5 m/s

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