_________ was the first to show that all objects fall toward Earth with constant ____________.

Sir Isaac Newton was the first to show that all objects fall toward Earth with a constant acceleration. To understand how he arrived at this conclusion, we need to examine Newton's second law of motion, which states that the force acting on an object is equal to its mass multiplied by its acceleration (F = ma).

In the case of objects falling toward Earth, there is a force acting on them known as gravity. Newton discovered that the force of gravity on an object near the surface of the Earth is equal to the object's mass multiplied by the acceleration due to gravity (g). This can be expressed as F = mg, where m is mass and g is the acceleration due to gravity.

So, to find the acceleration due to gravity, we can rearrange the equation to solve for it: g = F/m. Newton conducted experiments using objects of different masses and observed the acceleration with which they fell. He calculated the force of gravity acting on each object by measuring their masses and multiplying them by the acceleration they experienced.

Newton's experiments led him to conclude that the acceleration due to gravity is the same for all objects near the surface of the Earth. He found that this constant acceleration, denoted as "g," is approximately 9.8 meters per second squared (9.8 m/s²). Therefore, all objects fall toward Earth with a constant acceleration of approximately 9.8 m/s², regardless of their mass.

In summary, Sir Isaac Newton was the first to demonstrate that all objects fall toward Earth with a constant acceleration, and he arrived at this conclusion through experiments and calculations involving the relationship between force, mass, and acceleration.