Asubway train starting from rest leaves a
station with a constant acceleration. at the
end of 7.13 s, it is moving at 12.4062 m/s.
what is the train's displacement in the first
4.91257 s of motion?
answer in units of m.

Displacement = 20.996 m

Explanation: v = 12.4062 m/s ; t = 7.13 s

v= u + at

Here u = 0 ( Since it starts from rest)

  substituting the values

12.4062 = 0 + a × 7.13

Therefore a =

                    = 1.74

Now use,

s = ut + at²

Where u = 0

s = 0 + × 1.74 × 4.91257 × 4.91257

 = 20.996 m