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Solar Cooker Data. Time Plain Insulated ( o C) ( o C) 0 23 22 2 29 30 4 32 36 6 33 40 8 34 43 10 35 45 12 35 46 14 35 47 16 35 47. Time Plain Insulated ( o C) ( o C) 18 35 47 20 35 47 22 35 47 24 35 47 26 35 47. Energy Resources.
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Solar Cooker Data Time Plain Insulated (oC) (oC) 0 23 22 2 29 30 4 32 36 6 33 40 8 34 43 10 35 45 12 35 46 14 35 47 16 35 47 Time Plain Insulated (oC) (oC) 18 35 47 20 35 47 22 35 47 24 35 47 26 35 47
Energy is the capacity to do work. Energy is measured in Joules 1 Joule of energy can raise 1 N of weight exactly 1 meter 1 J=1N•m (PS: your diet offers ~5-10 million J/day)
First Law of Thermodynamics Energy can neither be created nor destroyed. It can be converted to another form.
Energy is the capacity to do work. Forms include:
Energy is the capacity to do work. Forms include: • Kinetic energy • Potential energy • Chemical energy • Heat • Elastic potential energy • Electrical energy
Energy is the capacity to do work. Together, these are called “mechanical energy” Forms include: • Kinetic energy • Potential energy • Chemical energy • Heat • Elastic potential energy • Electrical energy Friction converts kinetic energy to heat
Conversion of energy Electrical energy lifts cars
Conversion of energy Highest potential energy
Conversion of energy Highest kinetic energy
Conversion of energy potential kinetic
Conversion of energy kinetic potential
Heat: Rule 1 • All matter is composed of particles in constant motion
Heat: Rule 2 • Temperature is a measure of the kinetic energy of the particles.
Heat: Rule 2 (a and b) • Temperature is a measure of the kinetic energy of the particles. a) When you heat a sample, the particles speed up b) When you cool a sample the particles slow down
Heat: Rule 2 (a and b) • Temperature is a measure of the kinetic energy of the particles. a) When you heat a sample, the particles speed up b) When you cool a sample the particles slow down Absolute zero is the temperature at which the particles stop (-273oC)
Particles in motion: • Solid Liquid Gas
Heat transfer • Hot things cool and cold things warm up. • Duh.
Heat transfer • Hot things cool and cold things warm up. Three ways:
Heat transfer • Hot things cool and cold things warm up. Three ways: • Convection • Conduction • Radiation
Convection Heat is carried up by the hotter mantle material which is less dense.
Conduction Objects in contact Cold Hot
Conduction Not so cold Not so hot Cold Hot
Conduction Not so cold Not so hot Cold Hot Hot (fast) particles collide with cool (slow) particles. The fast ones slow down while the slow ones speed up
Conduction Not so cold Not so hot Cold Hot Fast (hot) particles collide with slow (cool) particles. The hot ones cool down while the cool ones warm up
Radiation • Heat is transferred by electromagnetic radiation—visible and not-so-visible light.
The electromagnetic spectrum Hot objects glow in visible light Warm objects “glow” in infrared light
Energy, Work, and Power • Energy . • Work . • Power
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done Work = Force x distance
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done Energy = the amount of work done Work = Force x distance
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done Energy = the amount of work done Work = Force x distance Power = work / time
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done Measured in Joules Measured in Joules Measured in Watts
Energy, Work, and Power • Energy—the capacity to do work • Work—exerting a force over a distance • Power—the rate of work being done Measured in J, kJ, cal, kcal, ft-lb, BTU, Q, kWh Measured in J, kJ, cal, kcal, ft-lb, BTU, Q, kWh Measured in W, hp, ft-lb/s
U&A Question 5 • 300 hp=300 x (550 ft-lb/s) =165000 ft-lb/s! • This motor could lift 165000 lbs at a rate of 1 ft/s (or) • 16500 lbs (a freight elevator) at 100 ft/s
To generate electricity… How would you like to heat your water?
Second Law of Thermodynamics When energy converted to another form, some of the energy is lost as unusable heat.
Second Law of Thermodynamics When energy converted to another form, some of the energy is lost as unusable heat. (or) Energy conversion is never 100% efficient.
Electricity • A generator generates electricity. • Work done on the generator is converted to electrical energy • You do work on the generator by turning the crank.
What turns your crank? • A turbine converts kinetic energy of a fluid into rotation. • Most electricity is made by steam driving a turbine
To generate electricity… How would you like to heat your water?
Options for turning a turbine Heatsteam
Options for turning a turbine Heatsteam • Coal • Natural gas • Nuclear fission • Biomass • Solar • Ocean thermal
Options for turning a turbine Heatsteam Direct • Coal 1) • Natural gas 2) • Nuclear fission 3) • Biomass • Solar • Ocean thermal
Options for turning a turbine Heatsteam Direct • Coal 1) Hydroelectric • Natural gas 2) Wind • Nuclear fission 3) Tidal • Biomass • Solar • Ocean thermal