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TOPIC 5: ENERGY
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BRAINSTORM: What do you know about ENERGY?
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ENERGY
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KINETIC POTENTIAL Energy of Motion “stored energy” VS. KE Low PE High
KE Increasing PE Decreasing KE Decreasing PE Increasing KE High PE Low
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Electromagnetic Energy (EME):
Energy that travels in the form of waves. Wavelength- distance between two crests or troughs. Frequency- number of waves passing a given point per second. As the wavelength increases, the frequency decreases (indirect).
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Electromagnetic Spectrum:
See reference tables diagram p. 14 The difference between the various forms of EME is their wavelengths.
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EME Facts: All EME travels at the same speed which is the speed of light (300,000 km/sec) Everything above absolute zero gives off EME. The higher the temperature, the more EME it gives off.
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INTERACTIONS: Reflection
Smooth, light colored surfaces are good reflectors. Absorption Rough, dark colored surfaces are good absorbers. Good absorbers of EME are good RADIATORS
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INTERACTIONS: Refraction Scattering Bouncing off at various angles.
The bending of EME. Ex. Prisms, Rainbows Bouncing off at various angles. Ex. Why the sky is blue.
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HEAT ENERGY: Heat- the average kinetic energy of molecules.
Why is heat considered a form of Kinetic Energy? What are the three methods by which heat can be transferred from place to place?
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HEAT TRANSFER: CONDUCTION:
Heat is transferred from molecule to molecule by contact Conduction works best in solids Why? Examples:
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CONVECTION: Heat is transferred due to differences in density.
Occurs in liquids and gasses only!!! Why? Examples:
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RADIATION: The transfer of heat in the form of waves (EME)
No molecules are needed!!! Radiation is the only method by which heat can be transferred through space. Why? Examples:
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Bonus: What color of the visible light spectrum has the highest frequency?
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Specific Heat Joule- unit of energy (heat) Heat Lost or Gained Formula
Heat=Mass x temp change x specific heat Examples:
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Specific heat – the amount of heat needed to change the temperature of 1 gram of a substance by 1o Celsius See reference tables p.1 Examples: The higher the specific heat, the harder it is to heat up Liquid water has the highest specific heat (4.18 Joules/gram∙o c)
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Heat Flow Heat is transferred from Hot to Cold or from Source to Sink.
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PHASE CHANGES SOLID LIQUID GAS
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Latent Heat: Defn: Heat lost or gained during a phase change.
Examples: See reference tables p. 1
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HEATING CURVE
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OPEN SYSTEM CLOSED SYSTEM
Heat lost by the source is greater than the heat gained by the sink. Some heat is lost. CLOSED SYSTEM Heat lost by the source is equal to the heat gained by the sink. No heat is lost Vs.
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Earth’s Energy: Most of the energy at the Earth’s surface comes from the Sun Energy beneath the surface is produced by nuclear fission
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BONUS: What is the name of the process
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CONTACT convection Density WORDSPLASH Conduction HEAT TRANSFER
WAVES SPACE Conduction HEAT TRANSFER RADIATION Solids CONTACT Density Liquids & gases convection
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BONUS: Explain the relationship between the mass and temperature of main sequence stars.
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