Your child comes home with questions about the different kinds of kinetic energy. So how do you distinguish between the many different types? You can use common examples to help your child understand the kinds of kinetic energy.
Kinetic energy, or the energy of motion, is the ability to do work. If you use a force across a distance, you do work in a scientific sense. If you slide a book across a table, you have used kinetic energy. The many kinds of kinetic energy include mechanical, electrical, radiant, and sound.
Four Kinds of Kinetic Energy #1- Mechanical kinetic energy is the most familiar and common example of kinetic energy. As an object moves, it has kinetic energy. In order to lift an orange over your head it takes a joule of work. Kinetic energy is measured in joules (rhymes with cool) or Newton-meters, with force measured in Newtons and distance measured in meters. A car accelerating at the same rate as a bicycle has more kinetic energy because it has more mass.
Four Kinds of Kinetic Energy #2- Electrical energy that moves through wires is measured in watts. A joule of work done in one second is a watt, which is named for James Watt, the inventor of the steam engine. Trains used to run using steam engines. If you lift a quarter-pound hamburger with cheese vertically, a distance of one meter in one second, you use a watt of power. Take a close look at a light bulb that is not in a lamp. You will see a number followed by “kw”, or kilowatts, on most light bulbs. Electric motors also have kilowatt ratings. A kilowatt is one thousand watts. Electrical power can also be described as the product of current, measured in amperes or amps, and potential, measured in volts.
Four Kinds of Kinetic Energy #3- Solar energy is the heat and light, or radiant energy produced by the sun. The sun does not burn like a fire does. Nuclear fusion creates the sun’s energy. Helium atoms are formed from lighter hydrogen atoms, in the process creating heat, light, and other particles.
Light energy is a form of radiant energy emitted by accelerating electric charges or the electrons of atoms. Light we see, or visible light, is a small portion of electromagnetic waves, which are partly electric and partly magnetic. Light moves through the vacuum of space or through a material as waves. A wave can be described as a back and forth motion or a vibration.
Light can also move as particles, or photons. Frequency measures how many complete vibrations occur in a given time period, usually a second. Hertz is the unit for frequency, named from Heinrick Hertz who demonstrated radio waves, a type of electromagnetic radiation in 1886. Electromagnetic waves range from the longest, radio waves, to the shortest, gamma rays. The lowest frequency of light that we can see is red and the highest is violet. AM radio waves are broadcast in thousands of hertz, or kilohertz. FM radio waves are broadcast in millions of hertz, or megahertz. Radar and microwave ovens operate in the gigahertz, or billions of hertz range. X-rays and even shorter gamma rays are used in chemotherapy. In a vacuum, all electromagnetic waves travel at the speed of light which is 300,000 km/s.
Heat energy is another form of radiant energy. If you have ever seen a shimmering effect above a paved road or parking lot on a hot day, you have seen heat waves. You can feel heat radiating from a candle flame, a fireplace, or a space heater. Most light bulbs heat up while they operate because the tiny wire inside each bulb, called the filament, heats up and glows.
Four Kinds of Kinetic Energy #4- Acoustic, or sound, energy begins with the vibration of an object. A guitar has strings that vibrate to produce sound. A clarinet has a vibrating reed while a trumpet has a vibrating column of air in the mouthpiece. The human voice has vocal chords. These vibrations start waves in the air. However, sound also needs something to move through, or a medium. There is no sound in outer space since there is nothing for it to travel through. Astronauts outside the space shuttle or the International Space Station use radio waves, a form of electromagnetic radiation, to communicate.
You can use common examples to explain the various kinds of kinetic energy to your child. The many forms of kinetic energy include mechanical, electrical, radiant (heat and light), and sound.