1. Gravitational force: The force of gravity is the force of attraction between two objects that have mass. The greater the mass of the objects, the greater the gravitational force between them.

2. Electrical force: The electrical force is the force of attraction or repulsion between two electrically charged objects. Opposite charges attract each other, while like charges repel each other.

3. Magnetic force: The magnetic force is the force of attraction or repulsion between two magnetic poles. North poles attract south poles, while south poles repel south poles.

4. Mechanical force: A mechanical force is a force that is exerted by contact between two objects. A mechanical force can be a push, a pull, or a twist.

5. Nuclear force: The nuclear force is the force that binds the protons and neutrons together in an atomic nucleus. The nuclear force is much stronger than the electrical force, but it only acts over very short distances.

6. Thermal force: Thermal force is a force resulting from the random motion of particles in a system. This results in brownian motion.