BY

MBILI N.E (201083646) AND

DUBAZANA N (201062405)

There are four Fundamental Forces of Nature

1. Nuclear Force

2. Electromagnetic Force

3. The weak Force

4. The Gravitational Force

Nuclear Force – is the strong attractive force between nucleons in the atomic nucleus that holds the nucleus together.

NUCLEAR FORCE

SOME IMPORTANT PROPERTIES OF A NUCLEAR FORCE ARE They are attractive in character.

They are charge independent.

It is the short range force.

They are extremely strong.

They are dependent on the on the spin of the nuclei.

ELECTROMAGNETIC FORCE Electromagnetic Force - is the force that causes the interaction between electrically charged particles, and the areas in which this happens are called electromagnetic fields.

SOME FUNCTIONS AND PROPERTIES OF AN ELECTROMAGNETICFORCE

Binds atoms and molecules together to form ordinary matter

Has strength of approximately times that of the nuclear force.

It is so much stronger than the Gravitational Force Obeys a Universe square law Operates between over the distance which are not very large. It is the long range force, in principle extending over infinite distance

THE GRAVITATIONAL FORCE Gravitational Force – is the force that holds all the objects onto the earth. The gravitational force can also be describes as the force of attraction between all masses in the universe, especially the attraction of the earth’s mass for bodies near its surface.

SOME FUNCTIONS AND PROPERTIES OF THE GRAVITATIONAL FORCE

Has the long range, that has a strength of only about times that of a nuclear force.

It holds the planets, stars and galaxies together. It exists where ever there’s matter. It’s related to weight, the gravitational force is directly proportional to the weight. The gravitational acceleration on earth is 9.8m/ , it’s represented as (g) , and on the moon it is about 1.6m/ . On a different astronomical body like Venus or the Moon, the acceleration of gravity is different than on Earth, so if you were to stand on a scale, it would show you that you weigh a different amount than on Earth.

THE WEAK FORCE The weak Force- The fundamental force that acts between leptons and is involved in the decay of hadrons.

SOME FUNCTIONS , IMPORTANCE AND PROPERTIES OF THE WEAK FORCE

It is responsible for nuclear beta decay (by changing the flavour of quarks) and for neutrino absorption and emission. It is mediated by the intermediate vector bosons (the W boson and the Z boson). It is weaker than the strong nuclear force and the electromagnetic force but stronger than gravity. it is only effective at very short distances (10-18 m). Beta decay is just one example of the weak force, During beta decay a neutron disappears and is replaced by a proton, an electron and a neutrino (anti-electron). If the weak force were not to exist, many types of matter would become much more stable. Without the weak force, the sun would cease to exist. The weak force allows the fusion of protons and neutrons to form deuterium. The excess energy from this fusion is the source of heat from the sun.

HOW DO WE CALCULATE THESE FORCES??

THE GRAVITATIONAL FORCE - In order to calculate the gravitational force between two objects with masses of m1 and m2 , the equation is:

Where:

G is the gravitational constant equal to

is the distance between the two objects

F is the magnitude of the force between the objects.

ELECTROMAGNETIC FORCE - The force of attraction (or repulsion) of two particles can be calculated using Coulomb’s law. The law states:

WHERE:

k is

q1 and q2 are the charges of particles 1 and particle 2.

r is the distance between the particles.

THE WEAK FORCE

Beta decay is just one example of the weak force. During beta decay a neutron disappears and is replaced by a proton, an electron and a neutrino (anti-electron). It is also proven that a down quark disappears and an up quark is produced. The up quark eventually turns into the electron and neutrino. This can all be illustrated using the diagram below.

Where: is the emitted boson n is the neutron is the electron is the anti neutrino

THE CONCLUSION

In order to be considered part of our universe an object must interact by means of one of the four forces. The identity of a particle is, in a sense, determined by what forces it can respond to. Gravity acts on mass-energy which all particles (even the massless photon) possess. Everything responds to gravity. Quarks, the heaviest constituents of matter, respond to all of the remaining three forces. Quarks are defined as those particles that possess strong, weak and electromagnetic charge. Charged leptons (such as electrons and muons) interact both weakly and electromagnetically. Finally the interaction-impoverished neutrinos (neutral leptons) possess only weak charge; the neutrino interacts only via gravity and the weak force.

REFERENCES

1. Davies, Paul (1986), The Forces of Nature, Cambridge Univ. Press 2nd ed.

2. R. Machleidt and I. Slaus, "The nucleon–nucleon interaction", J. Phys. G 27 (2001).

3. G.D. Coughlan, J.E. Dodd, B.M. Gripaios (2006). The Ideas of Particle Physics: An Introduction for Scientists (3rd ed.). Cambridge University Press. ISBN 978-0-521-67775-2.

4. http://www.mosaicsciencemagazine.org/pdf/m10_05_79_01.pdf

5. "Sir Isaac Newton: The Universal Law of Gravitation". Astronomy 161 The Solar System. Retrieved 2008-01-04.