280 likes | 898 Views
Introduction to Energy. 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
E N D
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?