Energy Transfer Subtitle

Objectives Review Earth System Review the Water cycle Go over heat transfer through conduction, convection, and radiation Review Greenhouse Effect July 22, 2012Footer text here2

What are the different systems of the Earth? A system is a set of interacting parts/members that form an integrated whole Think of the organ systems within your body and how they all have individual parts/organs but function as a whole

What are the different systems of the Earth? Atmosphere – “atmos” means vapor/gas; the gaseous envelope surrounding the earth Hydrosphere – “hydro” means water; all the water and the vapor in the atmosphere Cryosphere – “cryos” means ice/freezing; the region of the earth’s surface that is frozen throughout the year

What are the different systems of the Earth? Geosphere - “geo” means earth; the solid earth Biosphere – “bio” means living; the area in which there are living organisms

How is water transferred through Earth’s systems? The hydrologic (Water) cycle Evaporation – liquid to gaseous state Condensation – gaseous to liquid state Melting – solid to liquid state Freezing – liquid to solid state Transpiration – evaporation from plants Precipitation – from atmosphere back to geosphere/biosphere/hydrosphere

Transferred Thermal Energy Heat – is defined as energy transferred from one system to another when the systems are at different temperatures “Hot” and “cold” are used to compare one object’s temperature to another or its surroundings Ex: “It was really cold this morning” – no it wasn’t, the atmosphere was just a lower temperature than your body temperature

Why do some things feel hot, while others feel cold? When systems with different temperatures touch energy is transferred from the higher temperature system to the lower temperature system. Ex. Feet on a cold tile floor. Energy is drained from your feet to the tile floor making your feet feel colder. Ex. Your hand on a warm metal pot handle. Energy is gained from the handle to your hand making it feel warmer.

Explain why a doctor’s stethoscope feel cold when it touches your back? Answer the question in your own words

Other Important Information Heat always moves from a warmer place to a cooler place Temperature is a measure of the average kinetic energy of the particles in an object

Heat and Thermal Energy July 22, 2012Footer text here11 Thermal Energy – the total kinetic (moving) energy of the particles that make up a substance The amount of thermal energy an object has depends on two factors. The temperature - When two substances of equal mass have different temperatures, the substance with the higher temperature has more thermal energy The Mass - The greater the mass of a substance of a given temperature, the more thermal energy it has.

Thermal Energy Transfer Sketch and summarize the information in Figure 2. July 22, 2012Footer text here12

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What will happen if two objects at different temperatures come into contact? Answer question in your own words Other Important Information Heat always moves from a warmer place to a cooler place Specific Heat- the measure of the amount of energy required to increase the temperature 0f 1 g of substance by 1 o C July 22, 2012Footer text here14

What three examples of heat transfer are given? July 22, 2012Footer text here15

What are the three ways that thermal energy is transferred? Conduction Conduction – transfer of energy through materials touching All atoms are vibrating, which means they have kinetic energy. Hot atoms have more energy. When hot atoms bump into cold atoms, they transfer energy Closer atoms mean more collisions Conductor vs. Insulator

Conductor-allows energy in the form of heat, to be transferred within the material, without any movement of the material itself Insulator- material that does not allow a transfer of electricity or energy. Materials that are poor thermal conductors can also be described as being good thermal insulators. July 22, 2012Footer text here17

What are the three ways that thermal energy is transferred? Convection Convection – transfers heat through moving currents in gases or liquids Hot liquids and gases are less dense and rise. Cool liquids and gases are more dense and sink. These are convection currents.

What are the three ways that thermal energy is transferred? Radiation – transfers heat through electromagnetic radiation; occurs even in a vacuum (empty space), doesn’t need to transfer through contact of atoms All energy on earth comes originally from the sun. Space is a vacuum, so only radiation can travel through space to earth

Convection Currents : a current in a fluid that results from convection. July 22, 2012Footer text here20

Radiation and the Greenhouse Effect July 22, 2012Footer text here21

Define GREENHOUSE EFFECT exchange of incoming and outgoing radiation that warms the Earth Why would Earth be a cold, lifeless planet without our atmosphere? Answer in your own words Why are scientists concerned about the high levels of greenhouse gases in the atmosphere? Answer in your own words July 22, 2012Footer text here22

Heat and Temperature Change Why do you think the buckle feels hotter than the seat belt? Answer in your own words July 22, 2012Footer text here23

Thermal Conductivity the rate at which heat passes through a specified material, expressed as the amount of heat that flows per unit time through a unit area with a temperature gradient of one degree per unit distance. July 22, 2012Footer text here24

Thermal Conductivity Why did the buckle feel hotter even though the seat belt was the same temperature? It had more thermal conductivity July 22, 2012Footer text here25

Specific Heat specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius Other Important Information substances with high specific heat capacities take a lot of heat energy and therefore a long time to heat up and also a long time to cool down. Specific heat unit of measure is K July 22, 2012Footer text here26

Heat, Temperature, and Amount and Calculating Heat What are the three pieces of information needed to calculate heat? Heat energy = mass x specific heat capacity x temperature change To determine how much energy is needed to heat a cup of water to make tea, you need to know …. mass of water specific heat of water The initial and final temperature of water Example problem: How much heat energy is needed to raise the temperature of 3 kg of copper by 6 K? (Specific heat capacity of copper = 385 J/(kg K) Heat energy = mass x specific heat capacity x temperature change = 3 x 385x 6 = 6930J July 22, 2012Footer text here27