Potential and Kinetic Energy

What is Energy??? The ability of an object To do work

Two Main Types of Energy Potential Energy Kinetic Energy All Energy Gravitation Potential Energy Elastic Potential Energy Chemical Potential Energy

What is Potential Energy? oEnergy that is stored and waiting to be used later

What is Gravitational Potential Energy? oPotential energy due to an object ’ s position oP.E. = mass x height x gravity height x gravity Don’t look down, Rover! Good boy!

PE HeightMass Gravity  ARRGGGG!! NO TRIANGLE

Find the Potential energy of a 20 kg bag of dog food elevated 5 meters above the ground on a shelf. Mass = 20 kg Height = 5 m PE = mx g x h PE = 20 kg x 9.8 m/s 2 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 Height = 8800 m PE = mx g x h PE = 65 kg x 9.8 m/s 2 x 8800 m PE = J

What is Elastic Potential Energy? oPotential energy due compression or expansion of an elastic object. Notice the ball compressing and expanding

What is Chemical Potential Energy? oPotential energy stored within the chemical bonds of an object

What is Kinetic Energy? oEnergy an object has due to its motion oK.E. =.5(mass x speed 2 )

Depends on … Mass and Speed

KE = ½ mass x velocity 2 KE = ½ M X V 2 Mass = 44 kg Speed = 31 m/s KE = ½ M x V 2 KE =.5 x 44 kg x (31 m/s) 2 KE = J What is the kinetic energy of a 44kg cheetah running at 31 m/s?

KE = ½ mass x velocity 2 KE = ½ M X V 2 Mass = 400 kg Speed = 5 m/s KE = ½ M x V 2 KE = 400 kg x (5 m/s) 2 KE = J What is the kinetic energy of a 400kg elevator descending at a rate of 5 m/s?