Question

A train, 90 m long, stops in a station with its front buffers in line with a lamp-post on the
platform. Later it starts off with an average acceleration of 0.45 2 m/s . What will be its
speed in km/h, when the tail buffers pass the lamp-post?

Answer 1

so the distance traveled will be 90m, right?
v^2 = 2as

but you have garbled your acceleration, so maybe when you fix that, you can plug in your numbers.
when you find v, it will be in m/s, so convert that to km/hr