Question

what is meant by accelerations

Answer 1

Hey mate

Here is ur answer

The rate of change of velocity per unit time is known as acceleration.

It's SI unit is m/s^2

a= v-u/t

Answer 2

Acceleration of a body is a measure of how fast (means, at what rate) velocity of a body is varying.
mathematically,
if Velocity is a continous function in time (of course, it is)
a=dV/dta=dV/dt
As velocity is a vector quantity, acceleration is also a vector quantity.