Presented by Betsy Sanford High School Physical Science Energy Transfer Presented by Betsy Sanford High School Physical Science

Properties of Energy The ability to do work or cause change Not matter Does not have mass (no “stuff”) Does not have volume (does NOT take up space) Examples of Matter and Energy: A light bulb is made of matter; the light it gives off is energy A piece of wood is made of matter; when it burns it gives off energy (light and heat) A guitar is made of matter; when played, it gives off energy (sound waves)

History of Energy Usage Lots of ways to release energy to do work have been used throughout time: Physical Strength (humans, tools, animals) Machines (simple and compound) Fire, Wind, Water, Steam Electricity Fossil Fuels (gasoline, coal, natural gas) Nuclear Fission – splitting the atom Fusion – solar radiation results from the joining of atoms in the sun)

Types of Energy Sound (vibrations) Mechanical (motion = potential + kinetic) Electromagnetic Radiation (visible light, infrared light, ultraviolet light, microwaves, etc.) Sound (vibrations) Electrical (moving electrical charges; currents) Chemical (energy in the bonds between molecules) Nuclear (the fission or fusion of an atom’s nucleus) Thermal (heat due to motion of particles)

Energy Transfer Energy is transferred by two means Doing Work mechanical energy causing motion Heat Transfer flow of heat from one object to another an object has more thermal energy when hot than when cool molecules in motion will speed up and spread out as heat is gained happens in three ways: conduction, convection, or radiation

Heat Transfer Conduction – by contact Convection – by current molecules collide like billiard balls in a game of pool works best in materials that have simple molecule that are close together happens in solids, liquids, and gases Convection – by current movement of heat by liquid or gas wind currents water currents

Heat Transfer Radiation – through empty space the movement of electromagnetic waves when sunlight reaches earth when sunburn happens when infrared light rays strike an object and heat up examples: sun, light bulb, toaster, iron

Measuring Energy Heat – thermal energy Temperature – the measure of heat the amount of heat coming from an object Absolute zero is no heat at all being given off by an object (Kelvin scale)

Specific Heat Some objects heat up and cool down faster than others Example: land heats up and cools down faster than water (causes breezes at the coast) Thermal Conductor – an object that does not take long to transfer heat (metal pot on a hot stove) Thermal Insulator – an object that takes a longer time to transfer heat or transfers very little heat (an oven omit) Specific Heat – the energy require to raise the temperature of a given object (specific heat for iron/copper/anodized aluminum is lower than the specific heath for cloth)

Examples of Specific Heat Substance Specific Heat Cloth 1340 j/kg Iron 448 j/kg

Formula for Calculating Specific Heat Q = m x T x Cp Q = change in thermal energy m = mass of substance T = change in temperature (Tf – Ti) Cp = specific heat of substance

Calculating Specific Heat - Example: How much energy is needed to heat a cup of water to make tea? Formula: Q = m x T x Cp Mass = 0.2 kg Temp. before = 250 C. Temp. after = 800 C Specific heat of water = 4,184 J/kg●0C Fill in formula: Q = m x T x Cp energy needed: 4,184 ● 0.2 ● 55 = 46,024 J

Specific Heat Practice #1 Formula: heat (J)= mass x change in temperature x specific heat Q = m x T x Cp How much energy is needed to heat a 5 kg aluminum pie plate from 0 degrees Celsius to 80 degrees Celsius? Q = 5 x (80-0) x 897 Q = 358,800 J

Specific Heat Practice #2 Formula: heat (J)= mass x change in temperature x specific heat Q = m x T x Cp How much energy is needed to cool a 20 kg glass window from 92 degrees to 56 degrees Celsius? Q = 20 x (92-56) x 840 Q = 604,800 J

Law of Conservation of Energy proposed by Albert Einstein energy cannot be created or destroyed when energy decreases in one place, it increases in another converted or changed into another form total amount of energy remains the same nuclear energy is the exception to the Laws of Conservation of Matter and Energy scientists split tiny atoms (destroying matter, nuclear fission) stars fuse atomic nuclei (creating matter, nuclear fusion) both produce huge amounts of energy (creating energy) 

Importance of Energy Exit Ticket Why does energy matter? So, why study energy? Why is energy important? How is energy connected to what we have already studied this year? How do you interact with the various forms or types of energy? Give examples.