Energy: THERMODYNAMICS AND ENERGY CYCLE Earth Science

The Laws of Energy Law of Conservation Laws of Thermodynamics

Law of Conservation Law of Conservation = Energy is neither created nor destroyed in ordinary physical and chemical processes (non-nuclear) It simply changes form and moves from place to place

Laws of Thermodynamics Three Laws of Thermodynamics First Law of Thermodynamics (Law of Conservation) If energy is added to a system, one of two things must happen: Heat is produced Work must be done as a product The conversion is not 100% efficient Example: grass for cows, gas for cars, etc.

Laws of Thermodynamics 2. Second Law of Thermodynamics Heat flows from a warmer object to a cooler object until equilibrium (balance) is reached Example: An ice cube sitting on a hot sidewalk will melt into a little puddle Once the puddle and sidewalk reach the same temperatures, the overall heat flow will be zero

Laws of Thermodynamics 3. Third Law of Thermodynamics Absolute zero = absolute order Absolute zero (-273C or -455F) At absolute zero, atoms stop moving completely No system can ever reach absolute zero under natural conditions

What does this have to do with Earth Science? Convection currents drive plate tectonics Convection currents also drive global air circulation patterns and the weather Deep ocean currents And more!

Essential Question What is the relationship between the amount of energy and the temperature, volume, and speed?

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

ENERGY IN Energy goes into the Earth’s system through Nuclear Energy in two ways: Radioactive decay in the Earth’s core heats the interior. Energy (heat) is transferred to the surface causing earthquakes and volcanic eruption

2. Sunlight (visible light) As photons (“pockets” of light energy) hit the Earth’s surface, they are absorbed and radiated back to the atmosphere as longer wavelengths (infrared energy) This is how light is converted to heat and cause the convection in the atmosphere

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Atoms When energy is added, atoms become excited and begin to move faster and get farther apart

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Temperature Temperature = the measure of how fast the atom are moving The more energy put into the system, the faster the atoms move and the greater the temperature gets.

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Density Density = the measure of the number of atoms/molecules in a given space (volume) The faster the atoms move and the farther apart they get, the less there will be in the same area.

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Volume Increases Volume = space a set number of atoms/molecules occupy The farther apart the atoms the more space they take up

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Pressure Pressure = the measure of the effect of atoms pushing on or impacting a given space The more atoms pushing on a given space the higher the pressure

Pressure (continued…) Pressure will decrease as long as the atoms are able to move freely (open system) If the atoms are contained, the pressure will increase as the atoms move faster and have more impacts per unit of time (closed system) Think of a tea kettle vs. a pot of boiling water Tea kettle = higher pressure Pot = lower pressure

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

Energy Out As the energized atoms come into contact (conduction) with less energized atoms, they lose some of their energy to make the other atoms the same temperature As energy is lost, the atoms slow down and get closer together Temperature decreases as the atoms slow down Density increases and volume decreases as the atoms move closer together

Equilibrium and Homeostasis Nature wants everything to be equal and balanced What happens when hot water and cold water are mixed? The energy is spread evenly until the temperature is the same throughout.

Energy Cycle and Earth’s Systems Convection currents in the mantle drive plate tectonics Convection currents that form in the atmosphere drive weather patterns Ocean currents

Energy Cycle Energy in Atoms move faster and get farther apart Volume decreases Temperature increases Density increases Density decreases Temperature decreases Volume increases Atoms move slower and get closer together Pressure decreases in an open system increases in a closed Energy out

CRITICAL THINKING QUESTION What are convection currents? (Hint: currents are movements of water. Think about the definition of convection. What happens to water when it is heated? What happens to water when it is cooled?