Question

why do we use metre per second square as the unit of acceleration?

Answer 1

acceleration as we know in physics is the rate of change of velocity and sense we can define the rate of change of velocity as the final velocity minus initial velocity that is why it has metre square and the time in which it changes is the Delta time that is why it is metr per second square

Answer 2

we use metre per second square as the unit of acceleration whenever the unit of velocity is metre and the unit of time is second
because acceleration = velocity / time.