There are four fundamental forces that account for all the forms of pulling and pushing between things.
- Whenever there is a push-pull interaction between two objects, forces are being applied to each of them. When the interaction ceases, the two objects no longer experience the force and their momentum continues uninterrupted.
- On a macro-scale wherever there is a concentration of stuff, in planets, suns or galaxies, that is where most of the push-pulls happen.
- Everything everywhere is in motion.
- Nothing in the Universe is stationary unless its temperature is reduced to absolute zero. But nothing can be cooled to a temperature of exactly absolute zero.
- Motion applies to things like objects, bodies, matter, particles, radiation and space-time. We also refer to the motion of images, shapes and boundaries. So motion signifies a change in the position of the elements of a physical system. An object’s motion, and so its momentum stays the same unless a force acts on it.
The four fundamental forces of nature are:
- Gravitational force: Gravity is the phenomenon that causes things with mass or energy to gravitate towards one another. Planets, stars, galaxies, and even light are all affected by gravity. The effect of gravity on small things like human beings when in the vicinity of something big like a planet is obvious. It is the Moon’s gravity that causes ocean tides on Earth. Gravity accounts for physical objects having weight. Gravity has an infinite range, although its effects become weaker as objects get further away from one another.
- Weak Nuclear force: In nuclear physics and particle physics, the weak nuclear force explains the interaction between subatomic particles that is responsible for the radioactive decay of atoms. The weak nuclear force doesn’t affect electromagnetic radiation.
- Strong Nuclear force: The strong nuclear force holds matter together. It binds the sub-atomic particles, protons and neutrons, that form the nucleus of an atom. Whilst repulsive electromagnetic forces push them apart, the attractive nuclear force is strong enough to overcome them at short range. The range at work here is measured in femtometres. The nuclear force plays an essential role in storing energy that is used in nuclear power and nuclear weapons.
- Electromagnetic force: The electromagnetic force is the force that occurs between electrically charged particles, such as electrons, and is described as either a positive or negative charge. Objects with opposite charges produce an attractive force between them, while objects with the same charge produce a repulsive force. The electromagnetic force is carried by photons in the form of electric and magnetic fields that propagate at the speed of light.