What Are Non-Contact Forces?

Non-contact forces arise from long-range interactions, such as gravity and electromagnetism. Weight is an example of non-contact force, as objects are attracted to massive bodies without touching them.

All four fundamental interactions are technically non-contact forces, although those having long-range are more commonly attributed as such. Gravity is an attractive force that arises between all bodies that have mass. The magnitude of the force exerted on a body is proportional to the product of the masses of the two bodies divided by the square the magnitude of the distance between them.

Electromagnetism can result in either attraction or repulsion between bodies depending on whether charges are similar or dissimilar. Similar charges repel, whereas dissimilar charges attract one another. The magnitude of mutual attraction or repulsion is proportional to the product of the magnitudes of charge divided by square the distance. Electromagnetism is responsible for all electrical, magnetic, radio, microwaves and high-energy radiation phenomena. Electromagnetic forces mediate chemical, biological and electronic processes.

The strong and weak nuclear forces are both contact forces, although their ranges are limited to subatomic sizes. These non-contact forces mediate nuclear binding and beta decay respectively. In spite of its short range, the strong nuclear force is enormous enough to negate the electrostatic repulsion between the protons in a nucleus, which all have positive charge.