The acceleration due to gravity is not *exactly* 9.8 meters per second squared. It's a close approximation, but the actual value varies slightly depending on factors like:

* Altitude: Gravity weakens slightly as you move further away from the Earth's center.

* Latitude: Gravity is slightly stronger at the poles than at the equator due to the Earth's oblate shape.

* Local density variations: The density of the Earth's crust can also cause small fluctuations in gravity.

Here's the breakdown of why it's close to 9.8 m/s²:

* Newton's Law of Universal Gravitation: This law states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

* Earth's Mass and Radius: Earth has a large mass and a relatively small radius. This creates a strong gravitational pull at its surface.

* The Value of "g": The acceleration due to gravity ("g") is calculated using Newton's law and Earth's mass and radius. This calculation gives us a value close to 9.8 m/s².

Important Note: The standard value of 9.8 m/s² is a convenient approximation used for most calculations. For more precise work, you might need to consider the specific location and altitude for a more accurate value.