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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-.

Energy and Its Forms

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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:

• 1.

• 2.

• 3.

• 4.

### 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:

• 1.

• 2.

• 3.

### 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