Understanding the Forces

* Gravity: The object experiences a downward force due to gravity (weight). This force is calculated as:

* Force of gravity (Fg) = mass (m) * acceleration due to gravity (g) = 80 kg * 9.8 m/s² = 784 N

* Friction: The object experiences an upward force due to friction, opposing its motion.

* Net Force: The net force acting on the object is the difference between the force of gravity and the force of friction.

Newton's Second Law

Newton's Second Law states that the net force acting on an object is equal to its mass times its acceleration:

* Net force (Fnet) = mass (m) * acceleration (a) = 80 kg * 4 m/s² = 320 N

Finding the Friction Force

1. Net Force: We know the net force is 320 N.

2. Force of Gravity: We calculated the force of gravity as 784 N.

3. Friction Force: Since the net force is the difference between gravity and friction, we can find the friction force:

* Friction force (Ff) = Force of gravity (Fg) - Net force (Fnet)

* Ff = 784 N - 320 N = 464 N

Therefore, the friction force acting on the object is 464 N.