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ENERGY

Forms and Conservation. ENERGY. 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. What is Energy?. Energy is the ability to do work.

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ENERGY

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  1. Forms and Conservation ENERGY

  2. 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.

  3. What is Energy? • Energy is the ability to do work. • If an object or organism does work (exerts a force over a distance to move an object) the object or organism uses energy.

  4. Work is a transfer of energy. • Because of the direct connection between energy and work, energy is measured in the same unit as work: joules (J). An object that has energy has the ability to do work. 1 joule = 1 newton meter

  5. Kinetic Energy • Kinetic Energy is the energy of motion. An object must be in motion to have kinetic energy http://www.youtube.com/watch?v=IGQ5lkVHPwc

  6. The greater the mass of a moving object, the more kinetic energy it has. • Kinetic Energy • The faster an object moves, the more kinetic energy it has. • Kinetic energy depends on both mass and velocity. K.E. = ½ m

  7. Calculations A 50kg boy went jogging with his father. Both ran at a velocity of 5m/s. Find out the kinetic energy of the boy. K.E. = ½ m 2 625 (kg x m2/s2) or 625 J • Now let’s try to figure out the father’s kinetic energy if he has a mass of 100kg. 1250 J

  8. Potential Energy • 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 is stored energy as a result of position or shape. • Stored chemically in fuel, the nucleus of atom, and in foods.

  9. Gravitational • Potential Energy • Potential energy that is dependent on height is called gravitational potential energy. • A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy.

  10. Gravitational • Potential Energy • An object’s gravitational potential energy (GPE) depends on its mass, height., and acceleration due to gravity. • I. E. If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board. PE = mgh G stands for acceleration due to gravity. It’s value is 9.8 m/s2

  11. Calculations What is the potential energy of a 10 kg book that is placed on a shelf that is 2.5 meters high? PE = mgh= • 2) (2.5 m)= Remember g is the acceleration due to gravity a constant always equal to 9.8 m/s2 245 J

  12. Elastic • Potential Energy • Energy that is stored due to being stretched or compressed is called elastic potential energy.

  13. Forms of Energy • The major forms are: • Mechanical • Thermal • Chemical • Electrical • Electromagnetic • Nuclear • All energy can be classified as kinetic, potential or the energy fields such as electromagnetic.

  14. Mechanical Energy • When you kick a football, you give mechanical energy to the football to make it move. • Bouncing ball • Energy associated with the motion and position of objects. • Sum of an object’s kinetic and potential energy.

  15. Thermal Energy • The internal motion of the atoms is called thermal energy, because moving particles produce heat. • Thermal energy can be produced by friction. • Thermal energy causes changes in temperature and phase of any form of matter. • Fire

  16. Chemical Energy • Energy Stored in chemical bonds. • Chemical Energy is required to bond atoms together. • And when bonds are broken, energy is released. • Fuel and food are forms of stored chemical energy. • Wood, gas, food

  17. Associated with Electrical Charges. • Batteries convert chemical energy into electrical energy that you then use to power your small appliances. • Lightning is an example of electrical energy. Electrical ENERGY

  18. ELECTROMAGNETIC ENERGY • Form of energy that travels through space as waves. • Power lines carry electromagnetic energy into your home in the form of electricity. • Light is a form of electromagnetic energy. • Each color of light (Roy G Bv) represents a different amount of electromagnetic energy. • Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.

  19. Nuclear ENERGY • The nucleus of an atom is the source of nuclear energy. • When the nucleus splits (fission), nuclear energy is released in the form of heat energy and light energy. • Nuclear energy is also released when nuclei collide at high speeds and join (fuse).

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

  21. Energy conversions • 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). All forms of energy can be converted into other forms.

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

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

  24. Chemical  Thermal Mechanical

  25. 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-Potential Energy Conversion

  26. At the point of maximum potential energy, the car has minimum kinetic energy. Kinetic vs. Potential Energy

  27. Kinetic-Potential Energy Conversions • As a basketball player throws the ball into the air, various energy conversions take place.

  28. Ball speeds up Ball slows down

  29. It can only be converted from one form to another. • If energy seems to disappear, then scientists look for it – leading to many important discoveries. • (PE + KE) beginning = (PE + KE) ending Energy can be neither created nor destroyed by ordinary means. The Law of Conservation of Energy

  30. 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. The Law of Conservation of Energy • E = MC2

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