1 / 20

15.1 Energy and Its Forms

15.1 Energy and Its Forms. Avalanches have a great potential for danger, so scientists research when to cause them in order to keep skiers safe. Energy is the ability to do work. Energy causes change in Motion Sound Appearance. Work is a transfer of energy.

urbana
Download Presentation

15.1 Energy and Its Forms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 15.1 Energy and Its Forms • Avalanches have a great potential for danger, so scientists research when to cause them in order to keep skiers safe. • Energy is the ability to do work. • Energy causes change in • Motion • Sound • Appearance

  2. Work is a transfer of energy. • For example, marathon runners have a “carb-load,” or eat pasta the night before the race to be able to run 26.2 miles. • It does not take energy to sit (0 J of work done).

  3. Kinetic Energy • Kinetic energy is the energy of motion. • Kinetosmeans “moving” in Greek. • The kinetic energy of any moving object depends upon its mass and speed. • KE = ½ mv2 • KE = kinetic energy (J) • M = mass (kg) • V = velocity (m/s)

  4. Kinetic Energy Problems • The mass of an object is 2 kg. Its velocity is 4 m/s. What is its KE? • KE = ½ mv2 • KE = ½ (2kg)(4 m/s)2 • KE = ½(2)(16) • KE = 1(16) • KE = 16 J

  5. KE Problems • The KE of an object is 400 J. Its velocity is 10 m/s. What is its m? • KE = ½ mv2 • 400 = ½ (m)(10 m/s)2 • 400 = ½(m)(100) • 4 = 1/2(m) • m = 8 kg

  6. KE Problems • The KE of an object is 81 J. Its mass is 2 kg. What is its velocity? • KE = ½ mv2 • 81 = ½ (2kg) (v)2 • 81 = (1) (v)2 • 811/2 = (v2)1/2 • V = + or – 9 m/s

  7. Potential Energy • Potential energy is energy that is stored as a result of position or shape. • Examples are a stretched string, a diver at the end of the board, a car at the top of a roller coaster, etc. • Food is also potential energy (it is stored to be used later) and changes its chemical shape.

  8. Gravitational Potential Energy • Gravitational potential energy is potential energy that depends upon an object’s height. • Someone in a roller coaster car at the top of the first hill has no KE, but a large PE (high height). • An object’s gravitational potential energy depends on its mass, its height, and the acceleration due to gravity.

  9. Potential Energy Problems • PE = mgh • PE is in J • M is in kg • G is 10 m/s2 • H is in m

  10. PE Problems • A 2 kg object is placed atop a 4 m shelf. What is its potential energy? • PE = mgh • PE = (2)(10)(4) • PE = 80 J

  11. PE Problems • An object has 90 J of PE and is on a 3 m shelf. What is the object’s mass? • PE = mgh • 90 = (m)(10)(3) • 90 = 30 m • M = 3 kg

  12. PE Problems • A 2 kg object has a potential energy of 50 J. What is its height? • PE = mgh • 50 = (2)(10)(h) • 50 = 20 h • 2.5 m = h

  13. Elastic Potential Energy • The potential energy of an object that is stretched or compressed is elastic potential energy. • This includes anything that springs, such as stringed instruments (guitars, etc.) and bungee cords. • This also includes anything that bounces, such as a basketball.

  14. Forms of Energy • The major forms of energy are mechanical energy, thermal energy, chemical energy, electrical energy, electromagnetic energy, and nuclear energy. • These can be broken down to KE and PE.

  15. Mechanical Energy • The energy associated with the motion and position of everyday objects is mechanical energy. • This includes not only machines but also people on the move. • Some mechanical energies come from chemical energy being transformed.

  16. Thermal Energy • The total potential and kinetic energy of all the microscopic particles in an object make up its thermal energy. • High temperatures give off light (photons). • Transfer is from hot to cold. • Endothermic- takes in heat • Exothermic- gives off heat

  17. Chemical Energy • The energy stored in chemical bonds is chemical energy. • Broken bonds do work. • ATP becomes ADP. • Combustion of gasoline moves cars.

  18. Electrical Energy • The energy associated with electric charges is electrical energy. • Electrical forces are used to do work. • Examples are batteries and lightning. • Battery potential is measured in volts (V).

  19. Electromagnetic Energy • A form of energy that travels through space in the form of waves is electromagnetic energy. • This includes solar radiation, visible light, and x-rays. • X-rays were given the name because scientists don’t know what they are (x is a variable in Algebra).

  20. Nuclear Energy • The energy stored in atomic nuclei is known as nuclear energy. • The strong and weak nuclear forces store an extremely high PE. • Fission releases energy by splitting the nuclei. • Fusion releases energy when less massive nuclei come together. • The sun undergoes fusion of H into He.

More Related