Energy and Its Forms

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# Energy and Its Forms - PowerPoint PPT Presentation

Ch 15.1. Energy and Its Forms. Energy and Work. Work is done when a force moves an object a distance Work is a transfer of energy. Energy is the ability to do work Both measured in J. Kinetic Energy. Energy of motion Depends on mass and speed. KE = ½ mv2 SI Units: KE- m- v-.

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Presentation Transcript
Ch 15.1

### Energy and Its Forms

Energy and Work
• Work is done when a force moves an object a distance
• Work is a transfer of energy
• Energy is the ability to do work
• Both measured in J
Kinetic Energy
• Energy of motion
• Depends on mass and speed
• KE = ½ mv2

SI Units:

• KE-
• m-
• v-
KE Practice
• A 0.10 kg bird is flying at a constant speed of 8 m/s. What is the birds kinetic energy?
• Given:
• Formula:
• Solve:
Potential Energy
• Energy that is stored due to position or shape
• Stored energy turns into KE
Potential Energy
• PE that depends upon an objects height
• Increases with increased height
• PE = mgh

SI Unit

• m-
• g-
• h-
• PE that is stretched or compressed
• Object springs back to its original shape

Gravitational PE

Elastic PE

Forms of Energy
• Energy associated with motion and position of everyday objects
• Sum of PE and KE
• Total PE and KE of all the microscopic particles in an object
• Particles move faster, becoming warmer

Mechanical

Thermal

Forms of Energy
• Energy stored in chemical bonds
• Energy associated with electric charges

Chemical

Electrical

Forms of Energy
• Form of energy that travels through space in the form of waves
• Energy stored in the atomic nucleus
• Fission- releases energy, splits apart
• Fusion- releases energy, comes together

Electromagnetic

Nuclear

15.2

### Energy Conversion and Conservation

Conservation of Energy
• Energy cannot be created or destroyed
• It is transferred or converted
Energy Conversion
• Energy can be converted from 1 form to another
• Process of changing energy – energy conversion
• Gravitational PE converts into KE as an object falls
Energy Conversions
• Pendulums
• PE constantly converted back and forth to KE
• Stays in motion due to weight
• Pole Vaults
Energy Conversion Calculations
• KE + PE = KE + PE

(Beginning) (End)

• KE=
• PE=
Conversion Practice
• A 1.50kg brick is dropped from rest and hits the ground at a speed of 26m/s. Ignore air resistance, calculate PE before the brick was dropped.
• Given:
• Formula:
• Solve:
Energy and Mass
• Albert Einstein
• Theory of Relativity
• E = mc2
• Energy and mass are equivalent and can be converted into each other
• c= speed of light 3.0 x 108 m/s
Ch 15.3

### Energy Resources

Nonrenewable Energy
• Exists in limited quantities
• Once used, it can’t be replaced except over the course of millions of years
• Natural Gas
• Coal
• Uranium
• Also known as fossil fuels
Renewable Energy
• Can be replaced in relativity short periods of time
Renewable Energy
• Hydroelectric
• Energy from flowing water
• Solar
• Sunlight converted into useable energy
Renewable Energy
• Geothermal
• Thermal energy beneath Earths surface
• Others
• Biomass Energy
• Energy stored in living things
• Hydrogen Fuel
• Creates electricity by reacting hydrogen and oxygen
Conserving Energy Resources
• Reduce energy needs
• Increase the efficiency of energy use