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friction Causes some mechanical energy to change into thermal energy. Mechanical energy Total amount of kinetic and potential energy in a system. joule respiration SI unit of energy energy The ability to cause change. Gravitational potential energy Energy stored by things that are above earth. Potential energy Stored energy due to position. Elastic potential energy Energy stored by things that stretch or compress. Kinetic energy Energy in the form of motion. Chemical potential energy Energy stored in chemical bonds. calorie Unit used to measure energy in food. Law of conservation of energy Energy cannot be created or destroyed. Kilogram (kg) Standard unit for mass. m/s Standard unit for speed. m/s² Standard unit for acceleration. watt Standard unit for power. Newton (N) Standard unit for force. Joule (J) Standard unit for work. Meter (m) Standard unit for distance. Kelvin Standard unit for thermal energy. wedge Name the simple machine: ax screw Name the simple machine: incline plane wrapped in a spiral around a cylindrical post. Wheel and axle Name the simple machine: a steering wheel Inclined plane Name the simple machine: sloping surface used to raise an object. pulley Name the simple machine: grooved wheel with a rope, simple chain, or cable running along a groove. Thermal energy The sum of kinetic and potential energy of all the atoms in an object. Specific heat Amount of heat needed to raise the temperature of 1 kg of a material by 1⁰ C or K. heat Thermal energy that flows from something at a higher temperature to something at a lower temperature. temperature Related to the average kinetic energy of an object’s atoms or molecules. work Transfer of energy that occurs when a force makes an object move. g=9.8 m/s² mass height What three things are used to calculate gravitational potential energy? Friction (example: moving a tire) What can cause kinetic energy to change into thermal energy? True-when potential energy goes up, kinetic energy goes down and vice versa, but the total energy remains the same. True/False The mechanical energy of a system always remains the same. Throwing a ball upward. Give an example of kinetic energy being converted into potential energy. KE=1/2(80)(4.6)² Steps: 4.6 x 4.6 x 80 / 2 KE=846.4 J Calculate the kinetic energy of Sam, a 80 kg man running 4.6 m/s KE=1/2 m x v² GPE=9.5 x 9.8 x 2.5 GPE=232.75 J What is the gravitational potential energy of a 9.5 kg ball on top of a 2.5 m shelf. GPE=mgh g=9.8 m/s² It decreases If the mechanical advantage of a lever decreases, what happens to the output force? A compound machine A hand operated can opener is an example of what kind of machine? W=175 x 3.5 W= 612.5 J How much works is done in lifting a 175 N box onto a shelf 3.5 m high? Work=force x distance Simple machine A machine that does work with one main motion is a ______ _______. insulator A material that reduces the flow of heat by conduction, convection and radiation is called a/an ___________. convection The process of warm water rising and cold water sinking in the ocean is called _________. false True/False A high specific heat indicates that a substance will heat up faster than a substance of lower specific heat. copper Which is the best conductor of heat: air, water, copper or plastic? R-Value Higher R-value=better insulation The effectiveness of insulation is rated with a/an ________. false True/False Heat pumps convert thermal energy into mechanical energy/ matter The transfer of thermal energy by radiation does not require _________. false True/False Refrigerators and air conditioners are heat engines. As the lava heats up, it expands and becomes less dense Why does the lava in a lava lamp rise? hotter object to a cooler object The transfer of heat is from a _____ object to a ________ object. The molecules are moving faster causing the water molecules to collide more often with the dye. Why would food dye disperse more quickly in warm water than in cool water?