1. Bellringer: When do you use energy? Do you know any forms of energy?
STOTD

2. Things to know... Concept Symbol Units Kinetic Energy KE Joules (J)
Potential Energy PE
Heat Q
Height h
Meters (m)
Specific Heat c
J/g•°C or J/g•K
Temperature T
°C or K

3. Energy and Energy Transfer
Chapter 15 and 16

4. Energy Energy The ability to do work Measured in Joules (J)
Work = Transfer of Energy
end

5. Energy
Kinetic Energy (KE)
The energy of motion
end

6. Energy
An arrow with a mass of 0.07 kg flies through the air at 28 m/s. What is the kinetic energy of the arrow?
If a 200 kg log rolling down a mountain has J of kinetic energy, how fast is the log moving?
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7. Energy Potential Energy (PE) Stored Energy
Many types, but we use Gravitational Potential Energy
Remember
Fg = mg
Fg = weight!
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8. Energy
A rock with a mass of 45 kg is held 2 m above the ground. What is the rock’s potential energy?
A man weighing 420 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table?
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9. Types of PE Energy Electrical Elastic Gravitational Chemical Nuclear
Stored in an object's height
Chemical
Stored in chemical bonds
Electrical
Electric charges
Elastic
Stretching or compressing (a spring or a rubber band)
Nuclear
Stored in the nucleus of an atom
end

10. Energy The Law of Conservation of Energy
Energy cannot be created or destroyed, it can only be converted into another form
50 J
50 J
0 J
100 J
end

11. Energy 3 1 2 Point 3: Start: Point 1: Point 2: Ball is moving slower,
KE = 196 J
Ball has gained height,
PE = 980 J
Some KE  PE
Start:
Ball at rest,
KE = 0
Ball has height, PE = 1176 J
Point 1:
Ball is moving,
KE = 588 J
Ball has lost height,
PE = 588 J
Some PE  KE 3
Point 2:
Ball is moving faster,
KE = 1176 J
Ball has lost ALL height,
PE = 0 J
All PE  KE 1 2
end

12. Thermal Energy Heat Thermal Expansion Transfer of thermal energy
Moves from Hot Objects to Cold Objects
Temperature: the measure of how much thermal energy is in an object.
Thermal Expansion
When an object is heated, it expands (gets bigger)
In the winter, rings are lose on your fingers
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13. Bellringer: What is Heat? What are the units of measurement for heat?
A 5.0 kg flower pot is sitting on a ledge 3 m above the ground. What is the flower pot’s potential energy? What is it’s kinetic energy?
STOTD
**You will need a Calculator today!

14. Thermal Energy Specific Heat (c)
Heat needed to raise the temp. of a substance
Low Specific Heat = Less Energy Needed
Units: J/g∙°C
end

15. Thermal Energy Heat (Q) Measured in joules (J) or calories (cal)
1 Calorie (big C from food labels) = 1000 cal
end

16. Thermal Energy
A piece of iron has a mass of 500 g. If iron has a specific heat of J/g·°C, how much heat must be absorbed to raise the temperature by 95 °C.
100 g of water at 25 °C is placed in a cup. The cup is heated so the water is now at 60 °C. Specific heat of water is 4.18 J/g·°C. How much heat was absorbed by the water?
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17. Back to the Law of Conservation of Energy…
Have you ever ridden a rollercoaster?

18. Thermal Energy Calorimeter Measure changes in thermal energy
Uses the principle that heat flows from hot to cold
Calculates the energy of a substance by blowing it up to heat water
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19. Bellringer:
A man weighing 40 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table?
A piece of iron has a mass of g. If iron has a specific heat of J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C.
STOTD

20. Energy Transfer Conduction
Transfer of thermal energy by objects touching
Touch Hot Stove = Energy goes into your Hand
Conductor
Allows thermal energy to flow
Metal, Tile
Insulators
Does not allow thermal energy to flow
Wood, Styrofoam
end

21. Energy Transfer Convection
Transfer of thermal energy by particles moving around
Heat/AC is circulated through your house
Important in natural cycles (oceans, weather, magma)
end

22. Energy Transfer Radiation
Transfer of thermal energy by waves moving through space
All objects radiate heat
As an object gets hotter it gives off energy faster
end

23. Energy Transfer: Thermodynamics
Study of thermal energy changing to other types
3 laws of Thermodynamics
1st Law of Thermodynamics
Energy is conserved
Energy will change forms, but the total energy is always the same
2nd Law of Thermodynamics
Energy can flow from cold to hot objects, only by doing work
3rd Law of Thermodynamics
Absolute zero cannot be reached
end

24. An arrow with a mass of 0. 7 kg flies through the air at 21. 5 m/s
An arrow with a mass of 0.7 kg flies through the air at 21.5 m/s. What is the kinetic energy of the arrow?
If a 20 kg log rolling down a mountain has 540 J of kinetic energy, how fast is the log moving?
A rock with a mass of 4.5 kg is held 32 m above the ground. What is the rock’s potential energy?
A man weighing 40 N jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table?
A piece of iron has a mass of g. If iron has a specific heat of J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C.

25. Bellringer:
A piece of iron has a mass of g. If iron has a specific heat of J/g·°C, how much heat must be absorbed to raise the temperature by 15 °C.
STOTD

26. Bellringer:
How can energy be transferred from one object to another? (we mentioned three ways yesterday).
How does a roller coaster transfer energy?
STOTD