An object's motion is determined by the forces acting on it. According to Newton's First law of motion, an object in motion will remain in motion, and an object at rest will remain at rest unless acted upon by an external force. This means that objects will only move if there is a net force (a combination of forces) acting on them.

There are four fundamental forces in nature that govern the motion of objects:

1. Gravitational force: This is the force of attraction between two objects due to their masses. It is what keeps planets in orbit around the sun and objects falling toward the ground.

2. Electromagnetic force: This is the force of interaction between charged particles, such as protons and electrons. It is responsible for holding atoms and molecules together and for the properties of electricity and magnetism.

3. Strong nuclear force: This is the force that holds protons and neutrons together inside the nucleus of an atom. It is much stronger than the gravitational force, but only acts over very short distances.

4. Weak nuclear force: This is the force responsible for certain types of radioactive decay. It is much weaker than the strong nuclear force and acts over very short distances.

The motion of an object is determined by the vector sum of all the forces acting on it. If the net force is zero, the object will continue to move with constant velocity. If the net force is non-zero, the object will accelerate in the direction of the net force.

In addition to the four fundamental forces, there are other types of forces that can act on objects, such as friction, air resistance, and water resistance. These forces can affect the speed and direction of an object's motion, but they are ultimately caused by the four fundamental forces.