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Forms of Energy: Kinetic Energy, Gravitational Potential Energy, Elastic Potential Energy, Electrical Energy, Chemical Energy, and Thermal Energy

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Forms of Energy: Kinetic Energy, Gravitational Potential Energy, Elastic Potential Energy, Electrical Energy, Chemical Energy, and Thermal Energy 6/3/14 Objectives Forms of • State a practical definition of energy. energy • Provide or identify an example of each of these forms of energy: kinetic energy, gravitational potential energy, elastic potential energy, electrical energy, chemical energy, and thermal energy. Assessment Assessment 1. Which of the following best illustrates the physics definition of 2. Which statement below provides a correct practical definition of energy? energy? A. “I don’t have the energy to get that done today.” A. Energy is a quantity that can be created or destroyed. B. “Our team needs to be at maximum energy for this game.” B. Energy is a measure of how much money it takes to produce a product. C. “The height of her leaps takes more energy than anyone else’s.” C. The energy of an object can never change. It depends on “ D. That performance was so exhilarating you could feel the energy the size and weight of an object. in the audience!” D. Energy is the quantity that causes matter to change and determines how much change occur. Assessment Physics terms 3. Match each event with the correct form of energy. • energy I. kinetic II. gravitational potential III. elastic potential IV. thermal • gravitational potential energy V. electrical VI. chemical • kinetic energy ___ Ice melts when placed in a cup of warm water. • elastic potential energy ___ Campers use a tank of propane gas on their trip. ___ A car travels down a level road at 25 m/s. • thermal energy ___ A bungee cord causes the jumper to bounce upward. ___ The weightlifter raises the barbell above his head. • energy transformation ___ A spark jumps from the girl’s finger to the doorknob …….after she scuffs her feet on the wool rug. 1 6/3/14 Energy Mechanical energy Energy Mechanical energy Radiant energy Radiant energy Energy is the mediator of all Energy is the currency of change physical changes—such as in the physical world, similar to Nuclear energy Nuclear energy changes in speed, height, money being the currency of temperature, or chemical exchange in the economy. composition. Electrical energy Electrical energy Chemical energy Chemical energy Thermal energy Thermal energy Internal energy Internal energy of gases of gases The meaning of energy The meaning of energy Consider a 1 kilogram 0.0 J 0.0 J aluminum block at rest Move up 1 meter 9.8 J 9.8 J on the floor. It has zero joules of energy. 1 m Moving the block up one meter adds 9.8 J of energy. That energy has to be “spent” from another system. The meaning of energy The meaning of energy 0.0 J 0.0 J Move up 1 meter 9.8 J Move up 1 meter 9.8 J 9.8 J 9.8 J Increase speed to 2 m/s 2.0 J Increase speed to 2 m/s 2.0 J 11.8 J 11.8 J Move down 1 meter -9.8 J 2.0 J 0 m/s to 2 m/s 1 m An increase in speed from 0 to 2 m/s Now the block loses 9.8 J of energy “costs” an additional 2 joules, which by moving down, transferring the are added to the block’s energy. energy to another system. 2 m/s 2 6/3/14 The meaning of energy Energy 0.0 J 0.0 J Move up 1 meter 9.8 J Move up 1 meter 9.8 J Every physical change 9.8 J 9.8 J Increase speed to 2 m/s 2.0 J Increase speed to 2 m/s 2.0 J involves exchanges of 11.8 J 11.8 J energy. The amount of Move down 1 meter -9.8 J Move down 1 meter -9.8 J 2.0 J 2.0 J energy determines the Warm up by 5°C 4.5 J Warm up by 5°C 4.5 J 6.5 J 6.5 J amount of change. Finally, the block gains 4.5 joules of energy when it changes temperature by 5° C. 2 m/s Forms of energy Mechanical energy Mechanical energy Mechanical energy Radiant energy Radiant energy Energy comes in many forms. Mechanical energy includes Nuclear energy energy associated with motion Nuclear energy and position. Electrical energy Examples of mechanical energy Electrical energy include: Chemical energy • kinetic energy Chemical energy • gravitational potential energy Thermal energy Thermal energy • elastic potential energy Internal energy Internal energy of gases of gases Radiant energy Mechanical energy Nuclear energy Mechanical energy Radiant energy Radiant energy Radiant energy includes all Nuclear energy comes from the forms of electromagnetic Nuclear energy forces that hold the atomic Nuclear energy radiation. Examples include: nucleus together. • visible light Electrical energy Any change in an atom’s nucleus Electrical energy • infrared radiation absorbs or releases nuclear energy. • ultraviolet light Chemical energy Chemical energy • microwaves Nuclear energy is the energy Thermal energy source for the Sun and stars. Thermal energy • radio waves • x-rays Internal energy Internal energy of gases of gases 3 6/3/14 Electrical energy Mechanical energy Chemical energy Mechanical energy Radiant energy Radiant energy Electrical energy is carried by Chemical energy is energy stored electric currents. Nuclear energy in the bonds between atoms. Nuclear energy Electrical energy is clean, moves When chemical bonds are easily through wires, and is a key Electrical energy changed through chemical Electrical energy energy resource in human reactions, chemical energy is technology. Chemical energy released. Chemical energy Electrical energy must be derived Chemical energy is found in from other forms of energy, such Thermal energy foods and fuels. Thermal energy as nuclear or chemical energy. Internal energy Internal energy of gases of gases Thermal energy Mechanical energy Fluid pressure Mechanical energy Radiant energy Radiant energy Thermal energy is energy due to Fluid pressure in gases and temperature. Nuclear energy liquids creates a form of stored Nuclear energy energy. An object at a higher temperature has more thermal energy than if it Electrical energy The high-pressure air in a bicycle Electrical energy was at a lower temperature. tire has more energy (per cubic centimeter) than the lower- The thermal energy also depends Chemical energy Chemical energy pressure air outside. on the mass and material of the object. Thermal energy Thermal energy Internal energy Internal energy of gases of gases The meaning of Mechanical energy Assessment Radiant energy energy 1. Which of the following best illustrates the physics definition of energy? A. “I don’t have the energy to get that done today.” Nuclear energy T h Energy is the mediator of all physical changes, such as Electrical energy B. “Our team needs to be at maximum energy for this game.” changes in speed, height, T p temperature, or chemical Chemical energy composition. C. “The height of her leaps takes more energy than anyone else’s.” H Energy is measured in joules. Thermal energy D. “That performance was so exhilarating you could feel the energy in Internal energy the audience!” of gases 4 6/3/14 Assessment Assessment 1. Which of the following best illustrates the physics definition of energy? 1. Which of the following best illustrates the physics definition of energy? A. “I don’t have the energy to get that done today.” A. “I don’t have the energy to get that done today.” T This is a statement about how you are feeling – not about the physical h concept of energy. B. “Our team needs to be at maximum energy for this game.” B. “Our team needs to be at maximum energy for this game.” T T p t C. “The height of her leaps takes more energy than anyone else’s.” C. “The height of her leaps takes more energy than anyone else’s.” H H D. “That performance was so exhilarating you could feel the energy in D. “That performance was so exhilarating you could feel the energy in the audience!” the audience!” Assessment Assessment 1. Which of the following best illustrates the physics definition of energy? 1. Which of the following best illustrates the physics definition of energy? A. “I don’t have the energy to get that done today.” A. “I don’t have the energy to get that done today.” This is a statement about how you are feeling – not about the physical This is a statement about how you are feeling – not about the physical concept of energy. concept of energy. B. “Our team needs to be at maximum energy for this game.” B. “Our team needs to be at maximum energy for this game.” This concept of “excitement” and “readiness” is related to having physical This concept of “excitement” and “readiness” is related to having physical energy, but it does not express one of the fundamental forms of energy. energy, but it does not express one of the fundamental forms of energy. C. “The height of her leaps takes more energy than anyone else’s.” C. “The height of her leaps takes more energy than anyone else’s.” Height. Height is an indicator of potential energy. D. “That performance was so exhilarating you could feel the energy in D. “That performance was so exhilarating you could feel the energy in the audience!” the audience!” Assessment Assessment 1. Which of the following best illustrates the physics definition of energy? 2. Which statement below provides a correct practical definition of energy? A. “I don’t have the energy to get that done today.” This is a statement about how you are feeling – not about the physical A. Energy is a quantity that can be created or destroyed.
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