Here's why:

* Gravity: The primary force acting on a freely falling object is gravity. Near the Earth's surface, the acceleration due to gravity is approximately 9.8 m/s².

* Newton's Second Law: Newton's Second Law of Motion states that Force (F) equals mass (m) times acceleration (a): F = m * a.

* Calculation: In this case, the mass (m) is 1 kg, and the acceleration due to gravity (a) is 9.8 m/s². Therefore, the force (F) is:

* F = 1 kg * 9.8 m/s² = 9.8 Newtons

Important Note: This calculation assumes that air resistance is negligible. In reality, air resistance will play a role, and the net force will be slightly less than 9.8 Newtons.