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Energy Chapter 15 Science Journal Entry 22 • Describe two types of energy (energy sources for humans) and what you believe are the advantages and disadvantages of each type. Science Journal Entry 23 • Saving space between each question, create three interview questions about energy and types of energy. • Recording the name of the person that you have chosen to interview, record their answers to those 3 questions. The Relationship of Work and Energy • Energy is the ability to do work. Energy is transferred by a force moving an object through a distance. So when work is done on an object, energy is transferred to that object. Work is therefore the transfer of energy. Work and energy are measured in joules (J). Recall that a joule is equal to one newton-meter which is the amount of work done to move an object one meter with one newton of force. Kinetic Energy • Kinetic Energy is the energy of motion. Kinetic energy of any moving object depends upon its mass and speed. • Kinetic Energy (KE) = ½ mv2 • To Calculate the kinetic energy of an object in joules, multiply ½ by the object’s mass in kilograms (kg) and the square of its speed (v) in meters per second. Potential Energy • Potential energy is energy that is stored as a result of position or shape. Two forms of potential energy are gravitational potential energy and elastic potential energy. • Potential energy that depends upon an object’s height is called gravitational energy. When an object’s height is increased (placed at a higher elevation), the object’s gravitational potential energy is also increased. • https://youtu.be/T5WJoupRD8?list=PLGHu8MAwYEGgxW0L5xSyBGT0epUgu3xd 3:44 Gravitational Potential Energy • Gravitational Potential Energy depends on the mass, its height, and the acceleration due to gravity. The gravitational energy an object gains is equal to its weight (mg) multiplied by its height (h). Potential Energy (PE) = mgh • Gravitational potential energy is expressed in joules, the mass is expressed in kilograms, and the height in meters. The acceleration due to gravity, g, has a value in SI units of 9.8 m/s2. Height is measured from the ground or floor or some other reference level. • https://youtu.be/LrRdKmjhOgw?list=PLVtu2wHCw aF0qvxLz8TocuIwUmLgrBkhS 2:45 coaster Doing the Math • Example Problem: • A diver at the top of a 10 meter high diving platform has a mass of 50 kilograms. What is the diver’s potential energy? The formula is PE = mgh • What is used for the g in the equation? • What would be the total gravitational potential energy if the diver was standing at ground level? Elastic Potential Energy • Elastic potential energy is the potential energy of an object that is stretched or compressed. • A rubber band when stretched has elastic potential energy that immediately becomes kinetic energy when the rubber band is released. • Another example of elastic potential energy would be the strings of a musical instrument. A basketball has elastic potential energy since the compressed air in the ball forces the ball to spring back. • https://youtu.be/Jnj8mc04r9E?list=PLVtu2wHCwa F0qvxLz8TocuIwUmLgrBkhS 1:22 Wilie Mechanical Energy • Mechanical Energy is the sum of an object’s potential and kinetic energy. This energy is associated with the motion and position of everyday objects and is not limited to machines. Thermal Energy • Thermal Energy is the total potential and kinetic energy of all the microscopic particles in an object. Matter contains atoms that are always in random motion. When an object’s atoms move faster, the object becomes warmer and has a greater thermal energy. Chemical Energy • Chemical Energy is the energy stored in chemical bonds. This energy is released when the chemical bonds are broken. All chemical compounds store energy. Wood for campfires, coal and gasoline are all examples of substances that have the stored energy released by burning. Electrical Energy • Electrical Energy is the energy associated with electric charges. Batteries convert chemical energy to electrical energy to operate flashlights and calculators. In nature lightning bolts are produced by electrical energy. Electromagnetic Energy • Electromagnetic Energy is a form of energy that travels through space in the form of waves. Electromagnetic energy reaches earth as it is radiated by the sun. This radiation is able to travel through space not needing a medium to travel. Visible light and x-rays are two forms of electromagnetic energy. Many Forms of Radiation • All forms of electromagnetic radiation collectively are called the electromagnetic spectrum. Electromagnetic waves such as radio waves are used in communication since they can move long distances through air and space. Electromagnetic Spectrum Nuclear Energy • Nuclear Energy is the energy stored in atomic nuclei. The nucleus of an atom is held together by strong and weak nuclear forces giving it great potential energy. • Nuclear energy is released by two processes: fission and fusion. Energy is released in fission by splitting apart atomic nuclei. It is the process used by nuclear power plants to generate electricity. The sun uses the process of fusion to generate energy. Fusion occurs when less massive nuclei combine to form a more massive nucleus. Quick Review • What type of energy is used in fireworks? • What type of energy is used within the sun? • What type of energy is evident in lightning bolts? • All forms of energy can be converted into other forms of energy.