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Energy

Energy. What is energy?. Every change that occurs… big or small… requires energy. When something is able to change its environment or itself, it has energy. Energy is the ability to cause change. Examples…. What are some examples of having or using energy? A moving baseball

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Energy

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  1. Energy

  2. What is energy? • Every change that occurs… big or small… requires energy. • When something is able to change its environment or itself, it has energy. • Energy is the ability to cause change.

  3. Examples… • What are some examples of having or using energy? • A moving baseball • Combing your hair • Walking up the stairs

  4. Different Forms • There are different forms of energy. • When you turn on a light, the room gets brighter. • When you turn on your stereo, you hear sound.

  5. Think of money… • If you had $100, you can keep it… • In your wallet • In a bank account • In travelers checks • In gold and silver coins • The same is true for energy!! It can be found in different forms.

  6. Kinetic Energy • Kinetic energy is energy in the form of motion. • Wheels spinning • A sprinting runner • A train moving

  7. Kinetic Energy • Kinetic energy depends on two quantities… • The mass of the moving object • The object’s velocity

  8. Kinetic Energy • The more mass an object has, the more kinetic energy it has. • The greater an object’s velocity is, the more kinetic energy it has.

  9. Kinetic Energy • Which one has the most kinetic energy? Velocity = 5 m/s Mass = 500 kg Velocity = 20 m/s Mass = 500 kg

  10. Kinetic Energy • Kinetic energy is measured in joules (J) • We use the following equation to calculate how much kinetic energy an object has: • Kinetic Energy = ½ (mass) x (velocity)2 • KE = ½ m v2 • KE (joules) = ½ m (kg) x v2 (m2/s2)

  11. Racecar • If a racecar with a mass of 800kg is traveling at 35 m/s… how much kinetic energy does the car have? • KE = ½ mv2 • KE = ½ (800kg) x (35 m/s)2 • KE = 490000 J or 490 kJ

  12. Potential Energy (PE) • Even motionless objects can have energy… the energy is stored in the object. • An apple hanging in a tree has potential energy because it has the ability to cause change, to fall to the ground. • Stored energy due to a position is called potential energy (PE).

  13. Elastic Potential Energy • Elastic potential energy is energy stored by something that can stretch or compress such as a rubber band or a spring.

  14. Chemical Potential Energy • Energy stored in chemical bonds is called chemical potential energy. • Chemical energy is stored in bonds that hold a molecule together and are released when the bond is broken.

  15. Gravitational Potential Energy • Gravitational potential energy (GPE) is stored by objects that are above the Earth’s surface. • The amount of GPE depends on: • The mass of the object • The acceleration due to gravity • The height above the ground

  16. Gravitational Potential Energy • To calculate the GPE of an object, we use the following equation: • GPE = mass x gravity x height • GPE = mgh • GPE (J) = m (kg) x g (m/s2) x h (m)

  17. Changing GPE • The GPE of an object can be changed by changing the height of the object. • When the height of the object is increased, the gravitational potential energy increases!!

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