Energy: Forms and Changes

Law of Conservation of Energy Energy cannot be created or destroyed. Many scientists believe there is a certain amount of energy in the universe and that energy just moves around changing from one form to another.

Law of Conservation of Energy Think of energy as money. If you have a $10.00 bill you could store it in your wallet, in your pocket, or in your bank account. You could change the $10.00 bill into two $5.00 bills. Did you lose any money? No, you just changed its form.

What are the two types of energy? Kinetic Potential

What is kinetic energy? Energy of motion Objects that have mass and velocity have kinetic energy. Examples: a windmill turning, a person walking, atoms moving, electrons moving in a circuit, vibrating sound waves, wind blowing, texting

What is potential energy? the energy an object has based on its position or its shape Examples: A kid sitting at the top of a slide has potential energy, energy stored in the bonds of atoms, a car filled with gasoline, a rollercoaster car at the top of a hill, a solar panel.

Classify the following as a type of potential energy or kinetic energy (use the letters K or P) A bicyclist pedaling up a hill An archer with his bow drawn   A volleyball player spiking a ball A baseball thrown to second base The chemical bonds in sugar

Classify the following as a type of potential energy or kinetic energy (use the letters K or P) The wind blowing through your hair Walking down the street Sitting in the top of a tree A bowling ball rolling down the alley A bowling ball sitting on the rack

This graph shows a ball rolling from A to G This graph shows a ball rolling from A to G. The ball starts at point A and rolls to point G. At what letter does the ball have the greatest kinetic energy? Which letter shows the ball when it has the maximum potential energy?

Forms Energy Chemical Electrical Mechanical Electromagnetic (light, radiant) Thermal (heat)

Chemical Energy Potential energy It is stored in the bonds of atoms and released during chemical reactions.

Chemical Energy Fuel (gas, coal) Food Batteries Matches

Mechanical Energy Energy due to a object’s motion (kinetic) or position (potential). A moving car has mechanical energy due to its motion (kinetic energy) A barbell lifted high above a weightlifter’s head has mechanical energy due to its vertical position above the ground (potential energy). Mechanical energy can be changed into other forms of energy.

Mechanical Energy Pedaling a bicycle Fan blades spinning Moving your arms

Mechanical Energy When you kick a football, you give mechanical energy to the football to make it move.

Mechanical Energy When you throw a balling ball, you give it energy. When that bowling ball hits the pins, some of the energy is transferred to the pins

Electrical Energy Kinetic energy caused by the movement of electrons, the negative part of an atom. Electricity is electrical energy and is transported through power lines and converted into other forms of energy..

Electrical Energy Electrical energy can be converted back into other forms of energy, like heat in an oven or light from a lamp. Lightning is electrical energy

Electromagnetic Energy also called light energy and radiant energy includes all parts of the electromagnetic spectrum.

Electromagnetic Energy It includes energy from gamma rays, x-rays, ultraviolet rays, visible light, infrared rays, microwave and radio waves. Electromagnetic energy can be converted into chemical energy during photosynthesis in plants. Electromagnetic energy is a type of kinetic energy.

Thermal Energy (heat energy) The heat energy of a substance is determined by how active its atoms and molecules are. A hot object is one whose atoms and molecules are excited and show rapid movement. http://www.indiana.edu/~oso/animations/energytransfer.html

Energy Conversion Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

Energy conversions All forms of energy can be converted into other forms. The sun’s energy through solar cells can be converted directly into electricity. Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).

Other energy conversions In an electric motor, electrical energy is converted to mechanical energy. In a battery, chemical energy is converted into electromagnetic (light) energy. The mechanical energy of a waterfall is converted to electrical energy in a generator.

Energy Conversions In an automobile engine, fuel is burned to convert chemical energy into heat energy. The heat energy is then changed into mechanical energy.

Chemical  Heat Mechanical

The Law of Conservation of Energy Energy can be neither created nor destroyed by ordinary means. It can only be converted from one form to another.