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2014 What is sound , light and energy Elena Sofía Patiño Guajardo 28/04/2014 Index What is sound ………………………………………1,2 What is energy …………………………………..3,6 What is sound ………………………………………….7 What is sound? Is the consequence of changing air pressure over time. All sounds are vibrations traveling through the air as sound waves. Sound waves are caused by the vibrations of objects and radiate outward from their source in all directions. A vibrating object compresses the surrounding air molecules (squeezing them closer together) and then rarefies them (pulling them farther apart). Although the fluctuations in air pressure travel outward from the object, the air molecules themselves stay in the same average position. As sound travels, it reflects off objects in its path, creating further disturbances in the surrounding air. When these changes in air pressure vibrate your eardrum, nerve signals are sent to your brain and are interpreted as sound. Sound is a form of energy, just like electricity and light. Sound is made when air molecules vibrate and move in a pattern called waves, or sound waves. Think of when you clap your hands, or when you slam the car door shut. That action produces sound waves, which travel to your ears and then to your brain, which says, "I recognize that sound. Sound is mechanical energy in the form of pressure variances in an elastic medium. These pressure variances propagate as waves from a vibrating source. Sound is a vibration that propagates as a mechanical wave of pressure and displacement, through some medium (such as air or water). Sometimes sound refers to only those vibrations with frequencies that are within the range of hearing for humans [1] or for a particular animal. What is energy? Energy is the capacity of a system to do work. That system may be a jet, carrying hundreds of passengers across the ocean. A baby’s body, growing bone cells. A kite, rising on the wind. Or a wave of light crossing a space. In moving or growing, each of these systems is doing work, and using energy. Every living organism does work, and needs energy from food or photosynthesis. Humans also create machines that do work for them, and that derive energy from fuels. Some of the many forms that energy takes are: Mechanical energy, which includes - Potential energy, stored in a system. - Kinetic energy, from the movement of matter. Radiant or solar energy, which comes from the light and warmth of the sun. Thermal energy, associated with the heat of an object. Chemical energy, stored in the chemical bonds of molecules. Electrical energy, associated with the movement of electrons. Electromagnetic energy, associated with light waves (including radio waves, microwaves, x-rays, infrared waves). Mass (or nuclear) energy, found in the nuclear structure of atoms. One form of energy can be converted to another form. This transfer is based on the law of conservation of energy—one of the laws of thermodynamics. Humans converted energy from one form to another when they lit the first fire. By burning wood, they released the chemical energy stored in the bonds of the wood molecules, generating thermal energy, or heat. Other examples? A battery generates electrons from chemical reactions, which are used to make electrical energy. A toaster takes electrical energy and converts it to heat. Your leg converts the chemical energy stored in your muscles into kinetic energy when you pedal a bicycle. Sound is a form of kinetic energy. Molecules of air are vibrated, causing them to move in wave patterns. When these waves hit the eardrum, they make it vibrate too. This vibration energy is turned into electrical energy impulses, which your brain interprets as sound. Many times, multiple conversions are involved. Consider nuclear power generation. Atoms in the nuclear fuel are split, releasing their nuclear (mass) energy and creating thermal energy. This heat energy is, in turn, captured in the form of steam and used to drive a turbine generator, creating kinetic energy. And, finally, this kinetic energy spins a magnetic field around a conductor, causing a current to flow—creating electrical energy. To measure energy, we use the "heating value" of the fuel, which indicates how much of a certain fuel is converted to how much heat. Common units of energy are the calorie and Btu. Physicists, who are scientists who study force, motion and energy, say that energy is the ability to do work, and work is moving something against a force, like gravity. There are a lot of different kinds of energy in the universe, and that energy can do different things. Energy can be found in many things, and takes many forms. There is a kind of energy called kinetic energy in objects that are moving. There is something that scientists call potential energy in objects at rest that will make them move if resistance is removed. Energy lights our cities, powers our vehicles, and runs machinery in factories. It warms and cools our homes, cooks our food, plays our music, and gives us pictures on television. Energy is defined as the ability or the capacity to do work. We use energy to do work and make all movements. When we eat, our bodies transform the food into energy to do work. When we run or walk or do some work, we ‘burn’ energy in our bodies. Cars, planes, trolleys, boats, and machinery also transform energy into work. Work means moving or lifting something, warming or lighting something. There are many sources of energy that help to run the various machines invented by What is the light? Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Electromagnetic radiation waves, as their names suggest are fluctuations of electric and magnetic fields, which can transport energy from one location to another. Visible light is not inherently different from the other parts of the electromagnetic spectrum with the exception that the human eye can detect visible waves. Electromagnetic radiation can also be described in terms of a stream of photons which are massless particles each travelling with wavelike properties at the speed of light. A photon is the smallest quantity (quantum) of energy which can be transported and it was the realization that light travelled in discrete quanta that was the origins of Quantum Theory. It is no accident that humans can ‘see’ light. The detection of light is a very powerful tool for probing the universe around us. As light interacts with matter it can be become altered and by studying light that has originated or interacted with matter, many of the properties of that matter can be determined. It is through the study of light that for example we can understand the composition of the stars light years away or watch the processes that occur in the living cell as they happen