5.
all objects, regardless of their mass, free fall with the same

a. energy

b. acceleration

c. speed

d. motion

All the objects, regardless of their mass, free fall with the same acceleration.

Explanation:  

Acceleration is the force/mass. Gravitational force is the force that is acting on object in free fall. As gravitational force is constant everywhere, and hence for an object with free fall, acceleration will be same because the acceleration and force are directly proportional to each other.

Imagine that you have dropped the ball from your building then the speed of the ball changes. And as speed of the ball changes, motion keeps on changing.

Now imagine you caught the ball from 3rd floor after dropping. Then you dropped again, and now caught the ball from ground the force in the hands you felt were different. So energy also keeps on changing in free fall.

B. acceleration

Explanation:

All objects regardless of their mass, shape, and size free fall towards the Earth with the same acceleration in the absence of air resistance.

This phenomenon was studied by the famous physicist Galileo in his Pisa tower experiment.

According to the gravitation force between two bodies, the force experienced by one body due to other is independent of its own mass.

The gravitational force is given by equation

                                  F =  GMm/r²

If F is the force acting on the smaller body of mass 'm', then

                                 F = ma

Therefore, the equation becomes,

                                ma = GMm/r²

                                  a = GM/r²

Here it is clear that the acceleration of the body is independent of its mass or the body itself, because no physical quantity of that body is expressed in that equation.

The acceleration at any point is only the inherent property of the Earth itself.