Question

a train starts from the raliway station attain a speed of 21m/sin one minute find it's acceleration

Answer 1

here u=0m/s, v=21m/s t=1 min=60 s
a=v-u/t
=21/60
=0.35m/s

Answer 2

Let's see the given data:

Final Velocity(v) = 21 m/s
Initial Velocity(u) = 0 m/s
Time (t) = 1 min or 60 seconds

We know,

Acceleration(a) = v-u/t
                         = 21-0/60
                         = 21/60
                         = 0.35 m/s²   ←  Ans