Physical Science Energy
The Law of Conservation of Energy states that energy can not be created or destroyed, but may change from one form to another. Therefore, the total amount of energy in the universe is constant.
Law of Conservation of Energy In 1905, Albert Einstein said that mass and energy can be converted into each other. He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created. 2 E = MC
Energy: Forms and Changes
Nature of Energy Energy is all around you! You can hear energy as sound. You can see energy as light. And you can feel it as wind.
Energy is the ability of an object to do work Energy is the ability of an object to do work. The SI unit for measuring energy is the Joule (j). 1 J is the amount of energy required to move a 1 N weight, 1 meter.
States of Energy The most common energy conversion is the conversion between potential and kinetic energy. All forms of energy can be in either of two states: Potential Kinetic
http://www.youtube.com/watch?v=vl4g7T5gw1M
Potential Energy Potential Energy is stored energy. Stored chemically in fuel, the nucleus of atom, and in foods. Or stored because of the work done on it: Stretching a rubber band. Winding a watch. Pulling back on a bow’s arrow. Lifting a brick high in the air.
Potential energy Examples: -a ball sitting on the top shelf -anything that is flammable -a skydiver ready to jump
P.E. due to the elasticity of a material is called elastic potential energy. Examples of E.P.E.: A drawn bow A rubber band A compressed spring
Chemical potential energy is energy released through a chemical reaction.
Gravitational potential energy is due to an objects position above the ground. Why does is burn when you slide down the rope in gym class?
Gravitational potential energy On Earth the acceleration of gravity is 9.8 m/s2, and has the symbol g.
Kinetic energy is energy in motion. The amount of kinetic energy which an object has depends on the objects mass and velocity. i.e. the bigger it is or the faster it is moving, the more kinetic energy it has.
What other property that we’ve talked about is kinetic energy closely related to?
Mechanical energy is the combined total of the kinetic and potential energy in an object or a system. K.E. + P.E. = M.E.
Example: A bouncing ball will continually alternate between kinetic and potential energy as it goes up and down. (Changing from one form of energy to another.)
Explain what happens to the kinetic, potential, and mechanical energies of a pendulum as it swings back and forth.
Kinetic-Potential Energy Conversion Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.
Kinetic vs. Potential Energy At the point of maximum potential energy, the car has minimum kinetic energy.
Kinetic-Potential Energy Conversions As a basketball player throws the ball into the air, various energy conversions take place.
Ball speeds up Ball slows down
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