As, the only force which is acting on body on free fall is Gravity.

Hence, its acceleration will also be relative to gravity.

If gravity is the only force acting on an object, then we find the object will accelerate at a rate of 9.8m/s � down toward the centre of the Earth (this is often rounded to 10m/s)

In fact, all objects will fall at this rate if the air does not act to slow them down.