# Examples

Relevance of Physics to Music

sound waves: Music is an artistic expression in the form of organized vibrations. Vibrating strings in string instruments and columns of air in wind instruments generate sound by vibrating at fundamental frequencies or multiples of these frequencies known as harmonics. An octave is a harmonic that is double or one half the frequency of a given note. Sound travels as longitudinal, compression waves, the frequency of which determines the pitch, and the amplitude of which determines the volume.

law or strings: The fist law of strings states that the frequency at which a string vibrates is inversely proportional to its length : f/f'=l'/l; where f = original frequency, f'= new frequency, l = original length, and l' = new length. Thus, one can play a higher note on a guitar, banjo, violin, or other stringed instrument by shortening the length of the string. To facilitate this, such instruments are equipped with narrow lateral ridges underneath the strings known as frets. The musician presses the wire against these frets to shorten the length of the string that is plucked. A second law of strings states that the frequency of a string is directly proportional to the square root of its tension : f/f'=/, where T represents tension. Thus, if the tension on a string is quadrupled, the frequency of the string is doubled (f'=(f)/). All string instruments are tuned by adjusting the tension of the strings.

Relevance of Physics to Art

frequency, wavelength, color: Red, green and blue are the fundamental colors of light, and by mixing them in different ratios, you can obtain any desired color. Stage lights, televisions, and monitors mix red, green and blue to get the desired colors by addition of lights. This is known as additive mixing. The mixing of red, green, and blue light produces white light. By contrast, cyan, yellow, and magenta are the three fundamental pigments that can be combined in different ratios to produce a wide variety of colors of paint, dye or ink. Pigments reflect light, and therefore, the more pigments present, the less light reflected. When pigments are mixed, colors are subtracted, The mixing of cyan, yellow and magenta pigments produces a black pigment that reflects no light. Artists who understand the properties of light and pigments can achieve the desired effects for their artwork.

center of mass: The center of mass is a point representing the mean position of the matter in a body or system. Many works of art rely upon the principle that an object will return to stable equilibrium as long as its center of mass passes within the base of support or below the pivot point. Ancient sculptors used this principle to insure stability of sculptures, and more recent art such as Alexander Calder’s kinetic sculptures or mobiles (figure 4.4) are dramatic illustrations of this principle.

Relevance of Physics to Literature

physics terms: Physics terms are frequently used in literature to explain events in everyday life. For example, authors may use terms such as quantum leap, free fall, light years, black holes, leverage, force, power, inertia, energy, work, resonance, and phrases such as “on the same wavelength,” “magnetic attraction,” “gaining momentum,” and the “gravity of the situation” to explain by analogy to physics concepts.

physics authors: Great physics literature has had a profound influence on science and literature. Nicholas Copernicus (On the revolutions of the heavenly spheres, 1543), Johannes Kepler (A new astronomy, 1609), and Isaac Newton (Principia – Mathematical Principles of Natural Philosophy, 1687) are a few of the physics authors who popularized scientific writing as an acceptable literary form.

Relevance of Physics to Political Science

bosons / atomic structure - The Higgs boson is a hypothetical massive scalar elementary particle. To test for the existence of this particle and to further studies in the basic nature of matter, Congress approved the development of the Superconducting Super Collider (SSC), a multi-billion dollar facility. Various congressmen argued to have it in their district because of the prestige and jobs it would create, and eventually construction was started on an 87 km circumference underground collider in Texas. Debate again erupted in Congress, and in 1993 the project was canceled when it was decided the government did not have the funds build the SSC and the International Space Station simultaneously, leaving a 2 billion dollar hole in Texas.

nuclear x-ray laser - A nuclear X-ray laser was designed at Lawrence Livermore laboratories in California, and President Ronald Reagan was told of its potential for destroying enemy missiles. In his famous “Star Wars” speech, Reagan said:, "I call upon the scientific community who gave us nuclear weapons to turn their great talents to the cause of mankind and world peace: to give us the means of rendering these nuclear weapons impotent and obsolete." Reagan initiated the Strategic Defense Initiative (SDI), a multi-billion dollar program to develop this technology. There was much criticism of the program and it failed to achieve its goals before being abandon by the Clinton administration. The George W. Bush administration revived the program and the National Missile Defense, and in 2005 a test missile was intercepted using the physics principles discovered and the technology developed in the program.

Relevance of Physics to History

special relativity & nuclear fission: In 1905 Albert Einstein published his theory of Special Relativity, suggesting that a small amount of mass could be converted into a huge amount of energy (E=mc2). Further discoveries by physicists Ernst Rutherford, James Chadwick, Enrico Fermi, and Leo Szilárd produced further information about the nature of matter and the potential to develop a nuclear bomb. Albert Einstein warned President Roosevelt of the danger that the Nazis might develop a nuclear weapon, and the president decided to initiate the Manhattan Project that resulted in the design, production and detonation of three atomic bombs in 1945. The bombs hastened the end of World War II and opened the nuclear arms race of the Cold War between the Soviet Union and the United States.

levers & torque: The principle of leverage has been applied for thousands of years in the building of civilizations. The ancient Egyptians used levers to upright obelisks weighing in excess of 100 tons. In the third century BC, Archimedes wrote “Give me the place to stand, and I shall move the earth,” illustrating his understanding that levers can be used to multiply force (when the effort is farther from the fulcrum than the load). Alternatively, levers magnify speed if the effort is inside the fulcrum. First class levers (where the effort and load are on opposite sides of the fulcrum) are found in oars (used to move ancient galleys and modern row boats), trebuchets (medieval siege engines), and in many tools such as wrenches and pliers. Second class levers (where the effort is beyond the load on same side of fulcrum) are found in wheelbarrows and nutcrackers, and third class levers (where the effort is before the load on the same side of the fulcrum) are found in hoes, scythes, brooms, and catapults to amplify speed. Imagine how different the world would be if these tools were not developed.

Relevance of Physics to Sports

inertia: Inertia is a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force. Newton’s first law describes inertia: An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction, unless acted upon by an outside force. This principle is very important in contact sports such as football, and boxing. Football coaches recruit heavier players to serve as linemen, knowing that their greater mass will mean greater inertia and make it more difficult for the opposing team to penetrate the line. Boxers only compete against others in their weight class (bantamweight, featherweight, lightweight, middleweight and heavy weight) knowing that unequal weights would create uneven matches due to differences in inertia. Rotational inertia is useful in sports such as bicycling and ice-skating. Bicyclists maintain their upright position due to the rotational inertia of the wheels, and ice skaters adjust the rate of their spin by changing the moment of inertia as they move their arms or legs.

impulse and momentum. Momentum (p) is the product of mass and velocity (p=mv). Impulse (I) is the product of force and time (I=FDt, for constant force) and changes momentum FDt=mv. Baseball players want to increase the time of contact with the bat (Dt) to increase the velocity (v) imparted to the ball. When catching a ball, baseball players recoil to increase the time (Dt) of the impulse, and thereby decrease the force (F) necessary to stop the ball. Football running backs that have large mass (m) and are fast (v) will have greater momentum and be more difficult to stop.

Relevance of Physics to Home Economics

convection, conduction, radiation: Thermodynamics studies the movement of energy and the effect of energy on movement. Thermodynamics helps us understand how conventional ovens, convection ovens, and microwave ovens work. Conventional ovens transfer heat to food by radiation (radiant energy from the flame or heating element reaches the food), convection (warm air in the oven moves past the food, transferring energy to it), or conduction (metal racks or pans conduct heat to the food. Convection ovens are more effective because they have fans that move air past the food. Microwave ovens send microwave radiation (2450 MHz) through food. Water, sugar, and fat molecules absorb energy through dielectric heating as they vibrate in the alternating electric field induced by the oven.

thermal conductivity: Thermal conductivity is an intensive property of matter that describes the tendency to conduct heat. Copper has a thermal conductivity of 386 W·m-1·K-1 while iron has a conductivity of only 80 W·m-1·K-1. To increase the transfer of heat to food, manufacturers coat the bottoms of pots and pans with copper. To increase the speed of cooking turkeys or other large items, cooks use aluminum cooking pins that conduct heat into the food.