Physics For Industries

INTRODUCTION

Physics attempts to describe the fundamental nature of the universe and how it works, always striving for the simplest explanations common to the most diverse behaviour. For example, physics explains why rainbows have colours, what keeps a satellite in orbit, and what atoms and nuclei are made of. The goal of physics is to explain as many things as possible using as few laws as possible, revealing nature's underlying simplicity and beauty. Physics has been applied in many industrial fields, which include the air industry, construction industry, automobile industry, manufacturing industry and many others. All these industries apply physics in one way or another. For example a car that moves from one point to another has to have an engine that provides the momentum. The calibration of the engine together with the combustion of the fuel has to have a mechanical force that will move it.

Physics has helped shape the industries in making work easier. This will be highlighted with some of the industries that have used physics practically to achieve an objective.

Power generation industries

Physics behind solar Power Generation in Space shuttles

Solar arrays produce electrical power directly from sunlight. According to Green (1982), most long-duration space missions use solar arrays for their primary power. Most designs use photovoltaic cells to convert sunlight into electricity. They can be made from crystalline silicon, or from advanced materials such as gallium arsenide (GaAs) or cadmium telluride (CdTe). The photovoltaic cells with the highest efficiency use several layers of semiconductor material, with each layer optimized to convert a different portion of the solar spectrum. The solar intensity at Earth's orbit is 1,368 watts per square meter, and the best photovoltaic cells manufactured today can convert about a third of the solar energy to electrical power. For electrical power when the Sun is not available (for example, when a space vehicle is over the night side of Earth), solar power systems typically use rechargeable batteries for storage.

According to Glaser, Davidson, and Csigi (1993), solar power systems can also be designed using mirrors or lenses to concentrate sunlight onto a thermal receiver. The heat produced by the thermal receiver then is used in a heat engine, similar to the steam turbines used in terrestrial power plants, to produce power. Systems of this type can store power in the form of heat, instead of requiring batteries, but have not yet been used in space.

Nuclear power in space shuttles

Since solar power decreases with the square of the distance from the Sun, missions to the outer planets require an alternate power source. Green (1982) indicates that nuclear power systems can provide power even when sunlight is unavailable. Nuclear generators are categorized as "radioisotope" power systems, which generate heat by the natural radioactive decay of an isotope, and "reactor" power systems, which generate heat by a nuclear chain reaction. For both of these power systems types, the heat is then converted into electrical power by a thermal generator, either a thermoelectric generator that uses thermocouples to produce power, or a turbine. For radioisotope power systems, the most commonly used isotope is Plutonium-238. The plutonium is encapsulated in a heat-resistant ceramic shell, to prevent it from being released into the environment in the case of a launch accident. Such isotope power systems have been used on the Pioneer, Voyager, Galileo, and Cassini missions to the outer planets (Jupiter and beyond), where the sunlight is weak, and also on Apollo missions to the surface of the Moon, where power is required over the long lunar night.

Air travel

Physics behind airplanes

Air travel is one of the great triumphs of the 20th century. Every day hundreds of thousands of people are carried through the air to destination all around the world. In every case the flight of heavier-than-aircraft results from the flow of air around their wings.

Before their first powered flight in December 1903, the Wright brothers, according to Cutnell & Johnson (2001), tested many different wing shapes in a wind tunnel to find the shape that produced the most lifting force. The fluid moving over the top travels a greater distance than the moving just under the bottom of the wing. Consequently, the fluid moving over the top must travel faster in order to conform to the shape of the wing and still maintain the natural streamline. The shape of the wing also crowds the streamlines together above the wing, just as in the case of a constructing pipe. The result is that of the region immediately above the wing. Because the downward force on the top of the wing is less than the upward force on the bottom, a net upward force, or lift, arises from the airflow. (Beyond the airfoil the flowing air has a downward component of velocity. By Newton's third law, the reaction force to the net downward force exerted on the air is the lift.) For lift to occur, a flow of air is required relative to the wing. The lift occurs equally well for a wing moving through stationary air or for moving past a stationary wing.

In general, as the flow of air past the wing increases, both the lift force and the drag force (the resistance to forward motion) increases. According to Breithaipt (2000), aircraft wings are designed so that pilots can change the wing shape during flight, producing greater lift for the slower speeds of takeoff and landing and producing less drag at cruising extended backward and downward from the trailing edge of the wing, increasing lift by imparting a greater downward velocity to the air.

Automobile industry

Physics behind tires

Physics play a crucial role when it comes to the design of tires. A friction comes between the surface and the tire and helps to prevent skidding and allow you to control your car when turning and stopping.

According to Breithaupt (2000), the tread pattern of rubber tire plays a major role in determining their friction, or skid resistance. Under dry conditions on paved roads, a smooth tire gives better traction than a grooved or patterned tread because a larger area of contact is available to develop the frictional forces. For this reason, the tires used for auto racing on the tracks have a smooth surface with no tread design. Unfortunately, a smooth tire develops very little traction under wet conditions because a lubricating film of water between the tire and