Fundamental Interactions of Matter and Energy

The Four Fundamental Forces

We are surrounded by physical forces in everything that we see around us and everything we do. Our everyday activities and experiences like walking, feeling the sun’s energy, obtaining power in our homes, sending rockets in the sky, sticking magnets on a refrigerator, as well as the motions of the stars and planets, all are governed by four fundamental forces.

From weakest to strongest, these fundamental forces are –

1. Gravitational force
2. Weak nuclear force
3. Electromagnetic force
4. Strong nuclear force

Weak Nuclear Force

The Weak Nuclear Force has the shortest range – just 0.1% of the diameter of a proton. It is evidenced at a subatomic level and is responsible for the radioactive decay of atomic nuclei. Therefore, unlike the other fundamental forces which hold things together, the weak nuclear force is responsible for breaking up matter, or decaying. This decay is literally the change of one subatomic particle into another, such as a neutron changing into a proton. This starts a radioactive decay chain.

The weak nuclear force is at work at the very heart of the sun, causing it to burn. It is also at the heart of Thermonuclear Fusion, which is used to build nuclear weapons.

Strong Nuclear Force

This force holds the nucleus of an atom together. It is the strongest of the four fundamental forces, acting at very short range, typically the diameter of the nucleus of an atom. It is an attractive force. It binds all the subatomic particles of matter together. For example, it keeps the neutrons and protons together in the nucleus of an atom.

Check Point

1. The weakest fundamental force is –
   1. Weak nuclear force
   2. Electromagnetic force
   3. Gravitational force
   4. Strong nuclear force
2. The force is responsible for radioactive decay of subatomic particles is –
   1. Weak nuclear force
   2. Electromagnetic force
   3. Gravitational force
   4. Strong nuclear force
3. A field of moving charged particles can create which force?
   1. Weak nuclear force
   2. Electromagnetic force
   3. Gravitational force
   4. Strong nuclear force
4. The force keeping the nucleus of an atom together is the –
   1. Electromagnetic force
   2. Weak nuclear force
   3. Gravitational force
   4. Strong nuclear force
5. The force which holds planets, stars, solar systems and galaxies together is the –
   1. Electromagnetic force
   2. Weak nuclear force
   3. Gravitational force
   4. Strong nuclear force

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