Physics

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Light is a form of energy produced by many chemical reactions. The sun and other stars produce huge amounts of heat and light through fusion and are the source of most visible light in the universe. Other reactions that produce light are combustion and chemoluminescence.

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  • Does Light Always Travel at Light Speed?

    Q: Does Light Always Travel at Light Speed?

    A: Light typically travels at 186,000 miles per second, but scientists have found a way to slow it down to 38 miles per hour. A team at the Rowland Institute for Science has found a new state of matter to help slow light down. Sodium atoms were cooled almost to absolute zero, which is 459.67 degrees Fahrenheit below zero. That’s lowest temperature theoretically possible. They then shot a laser through the extremely cold sodium atoms, which acted like “optical molasses” to slow down the beam of light.
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  • How Are Mass and Weight Related to Each Other?

    Q: How Are Mass and Weight Related to Each Other?

    A: Mass and weight are closely related because mass affects the weight of an object experiencing the effects of gravity. Weight is the measure of the force of gravity on an object's mass, while mass is the measure of how much matter there is in an object.
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  • What Is the Difference Between Kinetic and Potential Energy?

    Q: What Is the Difference Between Kinetic and Potential Energy?

    A: Kinetic energy is contained in a moving object, while potential energy exists in a stored form. Potential energy can be changed into kinetic energy. Potential energy is ready for release, while kinetic energy is already doing work. The property of a body determines the type of energy it contains.
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  • What Are Some Good Lab Experiments That Explain Centripetal Force?

    Q: What Are Some Good Lab Experiments That Explain Centripetal Force?

    A: One good experiment that explains centripetal force is the spinning penny. A penny is put inside a balloon, and the balloon is filled with air. Then, the balloon is swirled around until the penny rolls around inside of the balloon. The penny continues to spin even after the swirling stops.
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  • Why Does Rubbing Your Hands Together Make Them Warmer?

    Q: Why Does Rubbing Your Hands Together Make Them Warmer?

    A: Friction causes the hands to warm up when rubbed together. The greater the amount of friction between two objects is, the more heat is generated.
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  • How Does a Fulcrum Work?

    Q: How Does a Fulcrum Work?

    A: A fulcrum is the fixed support or pivot point for a lever, which is a simple machine used to overcome resistance. The lever is a stiff rod or bar, and the location of the fulcrum determines the class of the lever. Levers are useful to increase force, increase speed or change direction of a force, according to HowStuffWorks.
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  • Why Does a Bouncy Ball Bounce so High?

    Q: Why Does a Bouncy Ball Bounce so High?

    A: Bouncy balls bounce high because the material of the ball is extremely elastic and can convert the kinetic energy from the fall into potential energy and back again with very little loss in momentum. Bouncy balls are used in many physics classrooms because they aptly demonstrate conservation of momentum through a highly elastic collision.
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  • What Is the Purpose of a Windmill?

    Q: What Is the Purpose of a Windmill?

    A: A windmill uses wind power to create rotational energy for the use in mills, pumps and presses. In the Netherlands, where windmills became important for local economies, they were used to make boards, paint, oil, paper and bread.
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  • What Are the Laws of Attraction and Repulsion?

    Q: What Are the Laws of Attraction and Repulsion?

    A: The Law of Attraction is the belief that a person's thoughts attract specific things, people and situations into his life. The Law of Repulsion is the belief that the more a person thinks about what he does not want, the more he attracts what he does want. According to SelfGrowth.com, both beliefs support the idea that what a person thinks about, negative or positive, can manifest into reality.
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  • What Were the Contributions of Archimedes to the Field of Physics?

    Q: What Were the Contributions of Archimedes to the Field of Physics?

    A: The first-century inventor and scientist Archimedes is remembered by physicists as the originator of the principles of mechanics, buoyancy, the lever and the pulley, according to Famousscientists.org. Perhaps his best-known contribution to physics is his discovery of the principle of displacement, which states that objects displace a volume of water equal to their own weight.
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  • What Are Examples of Noncontact Forces?

    Q: What Are Examples of Noncontact Forces?

    A: Electricity, gravity and magnetism are all examples of non contact forces. A force is anything that can cause a physical change in an object.
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  • What Are the Parts and Functions of a Theodolite?

    Q: What Are the Parts and Functions of a Theodolite?

    A: A thedolite is an instrument used to measure horizontal and vertical distances using lenses and lines. They include several components, such as a telescope, a leveling mechanism, a tripod and a compass. Theodolites are used for surveying and construction to obtain precise readings of landforms so construction projects remain level and plumb with the ground.
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  • What Is the Formula for Tension in Physics?

    Q: What Is the Formula for Tension in Physics?

    A: In physics, the tension on a suspended object said to be equal to the weight of the object plus or minus the mass of the object times the acceleration acting on it. In other words, this is the weight of the object plus or minus the force on it, depending on the direction in which the force is acting.
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  • How Does Gravity Affect Humans?

    Q: How Does Gravity Affect Humans?

    A: Humans evolved with gravity, and gravity affects human physiology and general health. Studies show that weightlessness has a number of negative health effects. Finding ways to mitigate these dangers is essential for long-distance space travel.
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  • What Is the Difference Between an Atomic Bomb and a Nuclear Bomb?

    Q: What Is the Difference Between an Atomic Bomb and a Nuclear Bomb?

    A: Although both atomic and nuclear bombs derive their immense power from reactions that take place in the nucleus of the atom, they do so in different ways. As the terms are most commonly used, an atomic bomb derives its energy from fission, or splitting atoms, while a nuclear device, or "H-bomb," is driven by fusion.
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  • Why Are Lasers Red?

    Q: Why Are Lasers Red?

    A: Lasers are mostly red in color because red has the longest wavelength, approximately 650 nanometers. Because of this, red does not scatter easily and can be viewed from a long distance.
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  • How Do Bullet Trains Work?

    Q: How Do Bullet Trains Work?

    A: Bullet trains, also called maglev trains, operate with magnetic levitation technology developed by Japanese and German engineers. Japanese engineers refer to their method as electrodynamic suspension while German engineers refer to their method as electromagnetic suspension. Either way, magnets raise the trains above the track, which means there is no need for wheels.
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  • How Did Albert Einstein Change the World?

    Q: How Did Albert Einstein Change the World?

    A: Time magazine named Albert Einstein the "Person of the Century" for the 20th century. Given his achievements as a physicist, the epochal impact of his ideas and theories, and his courageous personal and political stands on important issues, it is easy to see why Einstein was a top contender.
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  • How Does Light Make Colors Fade?

    Q: How Does Light Make Colors Fade?

    A: Light makes colors fade because ultraviolet radiation is capable of breaking down the molecules of pigments and dyes. The long molecules that make up these colors are often unstable, and the energy that ultraviolet radiation strikes these molecules with is capable of breaking the weaker molecular bonds in the structure. This degrades the colors over time, and as more molecules break down, colors begin to fade.
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  • Why Is a Current-Carrying Wire Normally Not Electrically Charged?

    Q: Why Is a Current-Carrying Wire Normally Not Electrically Charged?

    A: A current-carrying wire is not electrically charged because there are as many electrons as protons in the wire. As electrons flow in from one side, they flow out from the other, leading to no buildup of charge.
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  • Which Metal Conducts Heat the Fastest?

    Q: Which Metal Conducts Heat the Fastest?

    A: Silver is the metal that conducts heat the fastest. The thermal conductivity of silver is 420 W/ (m• K) or watts per meter degrees of Kelvin. Thermal conductivity measures the ability of heat or thermal energy to move through materials.
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