Potential & Kinetic Energy 1

Alabama Course of Study 10.) Differentiate between potential and kinetic energy. Examples: - potential-rock resting at the top of a hill, - kinetic-rock rolling down a hill 11.) Explain the law of conservation of energy and its relationship to energy transformation, including chemical to electrical, chemical to heat, electrical to light, electrical to mechanical, and electrical to sound. 2

Energy Energy- ability to do work 2 Types of Energy –Kinetic –Potential 3

Kinetic Energy Kinetic Energy- energy of an object of an object that is due to the object’s motion The object has kinetic energy if it is moving –Kinetic energy= –Kinetic energy increases as the mass or velocity increases mv² 2 4

Kinetic Energy What is the kinetic energy of a car has a mass if 1,200 kg and is moving at a speed of 20 m/s? KE= KE=(480,000 kgXm/s²) /2 KE=240,000 kgXm/s² Now do problems 1-4 on page 241 1,200 kg X (20m/s)² 2 1,200 kg X 400m/s² 2 5

Kinetic Energy A bowling ball has a mass of 20kg and it is traveling at 2 m/s. What is it’s kinetic energy? A car with a mass of 200kg travels with a velocity of 10 m/s. What is it’s kinetic energy? A skier with a mass of 15kg travels with a velocity of 9.9m/s. What is it’s change in velocity? 6

Potential Energy Potential Energy- energy that an object has because of the position, shape, or condition of the object The thing on earth that affects potential energy the most is gravity Height and weight after GPE the most –Gravitational potential energy=Weight X Height 7

Calculating GPE What is the GPE of a book with a weight of 13N at a height of 1.5m off the ground? GPE= Weight X Height GPE=13N X 1.5m GPE= 19.5 NXm or 19.5 J Now do problems 1-3 on page 242 8

GPE and Weight A 500N skier is 40m off the ground. What is his GPE? A 600N skier is 40m off the ground. What is his GPE? The skier with a higher ______ has the greater GPE. 9

GPE and Height A 500N skier is 40m off the ground. What is her GPE? A 500N skier is 60m off the ground. What is her GPE? The skier with a higher _______ has the greater GPE. 10

Elastic Potential Energy Elastic Potential Energy- energy associated with objects that can be stretched or compressed –Ex. When an archer pulls back a bow 11

Roller Coasters and Energy What energy is at the top of the roller coaster? What energy is at the bottom of the roller coaster? What energy is here? Or here? 12

Potential, Kinetic, or Both? Rock rolling down a hill Rock on the top of a hill You sitting in a chair You standing up A penny sinking in a cup of water Styrofoam ball floating in a cup of water Throwing a ball in the air 13

Mechanical Energy Mechanical energy-form of energy associated with position and motion of an object ME=PE + KE Ex. A football has 32 J of potential energy and 45 J of kinetic energy. What is the ME? 32J + 45J= 77J 14

You Teach Activity Green-thermal energy pg449 Yellow- electrical energy pg 450 Blue- chemical energy pg 450 Pink- nuclear energy pg 450 Orange- electromagnetic energy pg 450 Purple-Light energy (I will provide) Red- sound energy (I will provide) White- solar energy (I will provide) 15

4-5 Posters –No white –Must be named –Definition –1 fact –List 3 examples 16

Law of Conservation of Energy Law of Conservation of Energy- energy cannot be created nor destroyed but can change from one form to another When energy is changed from one form to another, it is called an energy transfornmation Most forms of energy can be transformed into other forms 17

Types of Transformations Single Transformation- one form of energy is changed into another one Ex. Cell phone transforms electrical to electromagnetic energy Multiple Transformations- more than change of form of energy –Match-chemical energy/to thermal(heat)/ electromagnetic(light) 18

Transformations between KE and PE One of the most common energy transformation is between potential energy and kinetic energy Look at pendulum on page 456 –Copy picture and words 19

Energy Transformations Chemical to Heat Chemical to Electrical Electrical to Light Light to Heat 20

More Energy Transformations Chemical to Electrical Electrical to Mechanical Mechanical to Sound 21