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## PowerPoint Slideshow about ' Introduction to Energy' - hafwen

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Presentation Transcript

What Is Energy?

- Changes are constantly occurring in the world.
- Every change requires energy.
- Energy – ability to cause change

Energy is Found in Many Forms

- Electromagnetic energy – energy in waves
- Mechanical – energy in physical movement
- Heat – thermal energy
- Nuclear – energy stored in the nucleus of an atom
- Kinetic – energy an object in motion has
- Potential – stored energy due to an object’s position

Units of Energy – the Joule

- Units of energy
- Kg * m2/s2
- Abbreviated J

Solving for Kinetic Energy

KE = ½ mv2

KE – kinetic energy (in J)

m – mass (in kg)

v – velocity (in m/s)

Example of Solving for Kinetic Energy

- A jogger with a mass of 60 kg is moving at a speed of 3 m/s. What is the kinetic energy?

Potential Energy

- Elastic potential energy – energy stored by something that can stretch or compress
- Chemical potential energy – energy stored in chemical bonds
- Gravitational potential energy – energy stored in objects due to their position above the Earth’s surface

Solving for Potential Energy

GPE = mgh

GPE – gravitational potential energy (in J)

m – mass (in kg)

g – 9/8 m/s2

h – height (in m)

Example of Solving for Potential Energy

- What is the gravitational potential energy of a ceiling fan that has a mass of 7 kg and is 4 m above the ground?

Changing GPE

- As an object begins to fall it has GPE and KE.
- As the object gets closer to the ground it has less GPE and more KE.
- Example – An 80 kg skydiver jumps from a 10 m platform. What is the GPE of the skydiver at the top of the platform? What is the GPE of skydiver after falling 5 m?

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