# Physics

Physics is defined as the “study of the laws that determine the structure of the universe with reference to the matter and energy of which it consists”1. In essence, it focuses on the study of the forces that exist in the natural world and the interrelationship between energy and matter. In the early days of the 20th century, physics was divided into six primary areas of study: light, magnetism, sound, electricity, and heat. Today, these areas have now been expanded to include areas such as relativity, string theory, quantum physics, and atomic physics.

The foundational nature of physics has undoubtedly contributed to its complexity and intrigue. It requires intensive empirical analysis and understanding in order to formulate a substantial and acceptable theory. We experience physics in action everyday in our daily lives when we walk, drive, jump, or when we simply drop an object. There are some basic laws of physics that set forth the framework upon which the subject of physics is constructed.

Basic Laws of Physics

Law of Gravity

This law states that any two objects exert a “gravitational force of attraction on each other. The direction of the force is along the line joining the objects. The magnitude of the force is proportional to the product of the gravitational masses of the objects, and inversely proportional to the square of the distance between them”.2 Hence, an object falling close to the surface of the earth will always fall at the same rate of acceleration, regardless of the object’s mass (ignoring air drag resistance).

It is calculated by: F = GmM/r²

F = force

G = gravitational constant

m and M = two masses (of the two objects)

r = the distance between the two objects

The gravitational constant is set at: 0.0000000000667390 (6.67390 x 10^-11)

Newton’s Laws of Motion

The issue with Newton’s laws of motion is that they normally apply to objects in a vacuum, and are therefore, difficult to observe in the real world. However, there are three structural theories that make it easier to understand the theories behind Newton’s laws of motion:

1. Any object at rest tends to stay at rest

2. The acceleration of an object is directly proportional to the force acting on it and inversely proportional to the mass of the object.

It is represented in the formula:

F = ma

F = force

m = mass

a = acceleration

3. For every action there is an equal and opposite reaction

Laws of Current Electricity

These laws deal with the manner in which electrons travel through a conductor and result in electrical current. There are two laws within the laws of current electricity that allow physicists to measure current, voltage, and power:

1. Ohm’s Law

I = V/R

2. Law of Electric Power

P = IV

P = power

I = current

V = volts

Two Basic Laws of Quantum Physics

Quantum physics is one of the more complex areas of physics. Quantum physics deals with light and matter at an atomic and subatomic level. Essentially, it “attempts to describe and account for the properties of molecules and atoms and their constituents—electrons, protons, neutrons, and other more esoteric particles such as quarks and gluons”.3

Two principles or laws that describe the behavior of matter at atomic and subatomic levels:

1. Heisenberg’s Uncertainty Principle:- Maintains it is impossible to fully pinpoint the speed, momentum, or position of subatomic particles such as electrons, all at the same time.

2. Pauli’s Exclusion Principle:- Maintains that two particles of matter such as neutrons, electrons, and protons cannot be in the exact same state. There are exceptions to this law, such as bosons and particles of force.

First and Second Laws of Thermodynamics

The First Law

This law states that all bodies contain heat at a certain level, regardless of how cold they are or may seem. The heat might be minute at a temperature close to absolute zero, but nevertheless, heat always exists. The implication is that as heat exists, and heat is a form of energy, one is able to conclude that energy is always conservable. This law relates closely to another law, referred to as the Conservation of Energy.

The Second Law

This law states that heat cannot travel from an area of low-temperature area to one of a higher-temperature. “Thus, all closed systems tend toward an equilibrium state in which entropy is at a maximum and no energy is available to do useful work. This asymmetry between forward and backward processes gives rise to what is known as the “arrow of time’”.4

The ultimate goal of physics is to develop a set of unified and consistent laws that govern the motion of all matter, energy, and motion existent within the universe. While such a goal is extremely ambitious, scientists have recently made great strides in the field, most notably recently, The Higgs Boson in Switzerland and NASA’s landing of Philae on the Comet 67P/C-G.

1. Daintith, J. (2005) Oxford Dictionary of Physics. New York: Oxford University Press

2. The University of Winnipeg

3. Quantum Mechanics

4. Thermodynamics

Physics Topics
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