The acceleration of a dense object during freefall is approximately 9.8m/s2 in the absence of all other forces except:

The acceleration of a dense object during freefall is approximately 9.8m/s^2 in the absence of all other forces except gravity. This is known as the acceleration due to gravity, and it is a constant value on the surface of the Earth.

Here are the steps to understand this concept:

1. Freefall is a state of motion where the only force acting on an object is gravity. This happens when an object is dropped from a certain height and there are no other forces acting on it, like air resistance or friction.

2. The force of gravity pulls the object towards the center of the Earth. This force causes the object to accelerate, or increase its speed, as it falls.

3. The rate of this acceleration is approximately 9.8 meters per second squared (m/s^2). This means that for each second the object is in freefall, its speed increases by about 9.8 m/s.

4. This value is an average as the actual acceleration due to gravity varies slightly depending on where on Earth you are (it's slightly stronger at the poles than at the equator).

5. If other forces are present, such as air resistance, they can slow down the object's acceleration. This is why a feather falls more slowly than a rock, even though they are both subject to the same acceleration due to gravity. The feather experiences more air resistance because of its shape and light weight.

6. In a vacuum, where there is no air resistance, all objects fall at the same rate regardless of their mass. This was famously demonstrated by astronaut David Scott on the moon, who dropped a feather and a hammer and found that they hit the ground at the same time.