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Potential and Kinetic Energy What is Energy??? The ability of an object To do work Two Main Types of Energy All Energy Potential Energy Gravitation Potential Energy Elastic Potential Energy Kinetic Energy Chemical Potential Energy What is Potential Energy? o Energy that is stored and waiting to be used later What is Gravitational Potential Energy? o Potential energy due to an object’s position Don’t look down, Rover! Good boy! o P.E. = mass x height x gravity ARRGGGG!! NO TRIANGLE Gravity PE Mass Height Find the Potential energy of a 20 kg bag of dog food elevated 5 meters above the ground on a shelf. Mass = 20 kg PE = mx g x h Height = 5 m PE = 20 kg x 9.8 m/s2 x 5 m PE = 980 J Find the potential energy of a 65 kg climber on top of Mt. Everest ( 8800 m high). Mass = 65 kg PE = mx g x h Height = 8800 m PE = 65 kg x 9.8 m/s2 x 8800 m PE = 5 605 600 J What is Elastic Potential Energy? o Potential energy due compression or expansion of an elastic object. Notice the ball compressing and expanding What is Chemical Potential Energy? o Potential energy stored within the chemical bonds of an object What is Kinetic Energy? o Energy an object has due to its motion o K.E. = .5(mass x speed2) Depends on … Mass and Speed KE = ½ mass x velocity2 KE = ½ M X V2 What is the kinetic energy of a 44kg cheetah running at 31 m/s? Mass = 44 kg KE = ½ M x V2 Speed = 31 m/s KE = .5 x 44 kg x (31 m/s)2 KE = 21 142 J KE = ½ mass x velocity2 KE = ½ M X V2 What is the kinetic energy of a 400kg elevator descending at a rate of 5 m/s? Mass = 400 kg KE = ½ M x V2 Speed = 5 m/s KE = 400 kg x (5 m/s)2 KE = 5 000 J