Things to know - Weebly
Transcript of Things to know - Weebly
Things to know…Concept Symbol Units
Kinetic Energy
Potential Energy
Heat
Height
Specific Heat
Temperature
Vocabulary:Energy Kinetic Energy (KE)Potential Energy (PE) Gravitational PEElastic PE Mechanical EnergyThermal Energy Chemical EnergyElectromagnetic Energy Nuclear Energy
Energy and Energy TransferEnergy and Energy Transfer
Chapter 15 and 16
Energy
n Energyn The ability to do workn Work = Transfer of Energy
end
Energy
n Kinetic Energyn The energy of motion
2
21 mvKE =
end
Energyn 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?
end
Practice
• If a 200 kg log rolling down a mountain has 50000 J of kinetic energy, how fast is the log moving?
Energy
• Complete #1-6 on “Kinetic Energy”
Energyn Potential Energyn Stored Energyn Many types, but we use Gravitational Potential Energy
mghPE = RememberFg = mg
Fg = weight!
hFmghPE g==end
Energy
n A rock with a mass of 45 kg is held 2 m above the ground. What is the rock’s potential energy?
end
Practice
• A man weighing 420kg jumps off a table that is 1.5 m high. What was his potential energy as he jumped off the table?
Energy
• Complete #1-7 on “Gravitational Potential Energy”
Energy
nTypes of PEnGravitationalnObject's Height
nChemical nChemical Bonds
n Electricaln Electric charges
n Elastic n Stretching/Compressing
(springs or rubber bands)
n Nuclearn Nucleus of an Atom
end
Energyn The Law of Conservation of Energy
n Energy cannot be created or destroyedn Can only be converted into another form
50 J 50 J
100 J0 Jend
EnergyStart:
Ball at rest,
KE = 0
Ball has height, PE = 1000 J
Point 1:
Ball is moving,
KE = 500 J
Ball has lost height,
PE = 500 J
Some PE à KE Point 2:
Ball is moving faster,
KE = 1000 J
Ball has lost ALL height,
PE = 0 J
All PE à KE
Point 3:
Ball is moving slower,
KE = 167 J
Ball has gained height,
PE = 833 J
Some KE à PE
1
end 2
3
Practice
• A 1000 Kg car is resting at the top of a 43 m hill. How much energy does the car currently have? What kind is it?
Practice
• An 80 Kg snowboarder is riding a half-pipe that is 15 m deep. If she begins at rest, how fast will she be traveling if there is no friction when she is at the bottom of the pipe?
Worksheet
• Law of conservation of energy worksheet.
Section Review
• P. 448 – Math Practice (1-3)
• P.452– Section Review 15.1 (1-5)
• Complete and Turn in with worksheet, done in class!
Bell Ringer
• What is Kinetic Energy? Formula?
• What is Potential Energy? Formula?
• What does the law of conservation of energy state?
Lab Safety Tip #
Design a Roller Coaster Lab
Warm-Up
• What does the law of conservation of energy state?
• A 1200 Kg car is resting at the top of a 65m hill. What kind of energy does it have? Calculate it.
Ch. 14 Quiz
Turn in When Complete and Finish Roller Coaster Lab
Bell Ringer
• What are some other types of Energy other than PE and KE?
• What are some ways to increase Energy?
• How does Temperature change as Energy increases or decreases?
Thermal Energy
n Specific Heat (c)n Heat needed to raise the temp. of a substancen Low Specific Heat = Less Energy Needed
end
Thermal Energy
n Thermal Expansionn Object heated à it expands (gets bigger)
n In the winter, rings are lose on your fingers
end
Thermal Energy
n Heatn Transfer of thermal energyn Moves from Hot Objects to Cold Objectsn Measured in joules (J) or calories (cal)
n 1 Calorie (big C from food labels) = 1000 cal
end
TmcQ ∆=Change in Temperature
Thermal Energyn A piece of iron has a mass of 500 g. If iron
has a specific heat of 0.449 J/g·°C, how much heat must be absorbed to raise the temperature by 95 °C.
end
Practice
n 100 g of water at 25 °C is placed in a cup. The cup is heated so the water is now at 60 °C. If c = 4.18 J/g·°C, how much heat was absorbed by the water?
Thermal Energy
• How much heat is given off when 5.0 g of water cool from 75 °C to 25 °C, if the specific heat of water = 4.18 J/g·°C.
• How many joules of heat are necessary to raise the temperature of 25 g of water from 10 °C to 60 °C, if the specific heat of water is 4.18 J/g·°C.
end
Worksheet
• Complete 1-5 Heat Calculations
Heat and Thermodynamics
Section 16.2
Thermal Energy Transfern3 Ways to Transfer Heat:nConductionn Objects Touchn Touch Hot Stove = Energy into your Hand
n Conductorn Lets heat flown Metal
n Insulatorsn Does not let heat flown Styrofoam
end
Thermal Energy Transfer
nConvectionnParticles moving aroundnHeat/AC in house/carnOceans, Wind
end
Thermal Energy Transfer
n Radiationn Infrared (IR) Wavesn All objects radiate heatn Hotter Objects = Give
off Energy Faster
end
Thermal Energy Transfer
n Thermodynamicsn Study of the transfer of thermal energy n 3 laws
n 1st Law of Thermodynamicsn Energy is conservedn Energy will change forms, but the total
energy is always the same
end
Energy Transfer
n 2nd Law of Thermodynamicsn Energy can flow from cold to hot objects,
only by doing workn 3rd Law of Thermodynamics
n Absolute zero cannot be reachedn We have reached 0.00000000045 K
end
Complete Today:Vocabulary: Only These• Heat, Temperature,
Absolute Zero, Calorimeter, Conduction, Thermal Conductor, Thermal Insulator, Convection, Convection Current, Radiation, Waste Heat, Heat Engine
• Complete Worksheet:specific heat
• Section Review: 16.1 & 16.2– P. 478 1-6
• (Read through the section to help find the answers!!!)
– Math Practice• p. 477 1,3,& 5
– 16.2: P.483 1-6