Physics Unit 6: Thermodynamics

1 / 12

# Physics Unit 6: Thermodynamics - PowerPoint PPT Presentation

Physics Unit 6: Thermodynamics. “Thermodynamics”. Is derived from Greek meaning “movement of heat.”. The First Law of Thermodynamics. Official Definition: When heat flows in or out of a system, the energy it gains or loses is equal to the amount of heat transferred. Or… Energy = Heat

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about ' Physics Unit 6: Thermodynamics' - shawn

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Physics Unit 6: Thermodynamics

“Thermodynamics”
• Is derived from Greek meaning “movement of heat.”
The First Law of Thermodynamics
• Official Definition:When heat flows in or out of a system, the energy it gains or loses is equal to the amount of heat transferred.
• Or… Energy = Heat
• Is analogous to the Law of Conservation of Energy
• We are now dealing with Internal Energy
Temperature:
• What is it?
• How “Hot” or “Cold” a substance is.
• Temperature represents the average translational kinetic energy of the individual particles in a system.
• The Temperature Scales
• Fahrenheit – water freezes at 32oF and boils at 212oF
• Celsius – Water freezes at 0oC and boils at 100oC
• Kelvin – is based off of Absolute Zero
• Absolute Zero
• So cold that all particles stop moving!
• Total energy of the particles is 0.
Specific Heat Capacity
• What is it?
• The resistance to change in temperature of a substance.
• The Equation:
• Q = mcΔTWhere: Q = heat addedm = mass of the samplec = specific heat capacityΔT = change in temperature
• Examples:
• How much heat energy is required in order to raise the temperature of a 0.5 kg iron nail from 25oC to 80oC?
• Q = mcΔTQ = (0.5)(460)(55) = 12,650 Joules
The Second Law of Thermodynamics
• Official Definition:Heat, of itself, never flows from a colder object to a warmer object.
• Energy always flows from Hot to Cold
• This law is also called the Law of Entropy
What is Entropy?
• The amount of disorder in a system
• The universe is always moving towards more entropy
• Examples:
• Ice melting
• Liquid water evaporating
• It takes Work (energy) to decrease Entropy
Types of Heat Transfer
• Conduction
• Heat transfer between materials that are in direct contact with each other.
• Convection
• Transfer in a fluid by movement of the substance itself.
• Energy transmitted by electromagnetic waves.
Phase Changes
• The States of Matter:
Phase Changes

Boiling

• Types of Phase Changes:
• Melting
• Evaporation
• Condensation
• Boiling
• Sublimation

Melting

Evaporation

Condensation

Sublimation

Phase Changes
• How do you change the melting point or boiling point of a substance?
• Change the pressure
Phase Changes
• Energy During Phase Changes
• What happens to the temperature of water as heat is added?
• It Increases.
• What happens to the temperature during a phase change?
• It remains constant.