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

2. 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)

3. 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)

4. 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)

5. 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

6. 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

7. 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

8. 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)

9. 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)

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

11. 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

12. 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

13. 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

14. 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

15. 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) 

16. 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.