From what i understand, you can calculate the impact force of a falling object hitting a surface using the impulse-momentum theorem.
So for example, if you dropped a $10\text{ kg}$ ball from a height of 2m onto a hard surface, the average force acting on the ball at impact would be
$$F_{avg}(t_2-t_1) = m(v_f-v_i) \\\implies F_{avg}=m\frac{\sqrt{2gh}}{t_2-t_1}$$
It is $F_{avg}$ that causes the ball to rebound (i.e. move in the opposite direction)
What I'm having a tough time grasping is that it seems like the rebound acceleration of the object due to this force is independent of mass.
$$F_{avg}=m\frac{\sqrt{2gh}}{t_2-t_1}=ma,\\ \text{so}~~ a=\frac{\sqrt{2gh}}{t_2-t_1}$$
Is that right? Am i missing something? Just like falling, all objects rebound at the same acceleration?