Contact and non contact forces

• A force is a personal pull that acts on an object due to its interaction with another object, and is measured in newtons.
• Forces also have direction, and can be classified as vector quantities because they have both magnitude and direction.
• Contact forces are those where the two objects are physically touching, while non-contact forces are those that don't require the two objects to be touching, such as friction, air resistance, and tension.
• The normal contact force, also known as the reaction force, is the force that the table exerts on the rock to keep it in position.
• Non-contact forces can act through empty space, and the three types you need to know are gravitational force, magnetic force, and electrostatic force.
• When discussing non-contact forces, it's often helpful to think of them as fields of influence around an object, as the forces can act on anything in that surrounding area.
• Gravity is a force of attraction between any two objects that have mass, and we would still feel this force of attraction even if we weren't touching the earth.
• Magnetic forces can be attractive or repulsive depending on the poles of the magnets.
• Electrostatic forces between charged objects can also be attractive or repulsive.
• The strength of a non-contact force will decrease as the objects get further apart.