Course Reflection
AK47
hacker_ch.7.pptxEnergy
Chapter 7 Hacker
ETSC 101 Chapter 7 Hacker
1
Energy Forms
Radiation
Thermal
Electrical
Mechanical
Chemical
Nuclear
ETSC 101 Chapter 7 Hacker
Broader View:
Kinetic - Movements
Potential – Attractions
Matter – the medium
Radiation: Light, heat, sound energy waves. Electromagnetic waves. Driven by attraction to a lower energy state, masses with lower energy. Without the mass, it must travel.
Thermal: Movement of atoms/molecules in a mass. Internal. Received energy excites atoms into movement.
Electrical: Electron attraction to a lower energy state resulting in movement.
Mechanical: Movement of mass driven by external force (movement of another mass) or gravitational attraction. Most often the product of an energy conversion.
Chemical: Atoms with an innate high energy attraction to a lower energy state, attraction to other atoms. Causes movement to a specific proximity of another atom forming a bond.
Nuclear: Caused by external movement force of neutron and repelling (opposite of attraction) of atomic structures to reach lower/stable energy state. To do this, after first initiated, enormous amounts of energy must be released. The external movement must be in put (energy in), the repelling force resulting is more energy than that input due to the natural repelling force.
Energy can be summed up in movements and attractions. All things desire the lowest energy state meaning no gradients between masses.
2
We Get Energy From One Source…
THE SUN
ETSC 101 Chapter 7 Hacker
Activity
Track the energy conversions from energy form to energy form from the energy path. (5 min).
Sun Plant coming to existence
ETSC 101 Chapter 7 Hacker
4
Fuels: Everything Takes Time
Non-renewable: Dead Things
Coal: Dead Organic Matter
Oil: Liquid Dead Organic Matter
Unstable Isotopes: Psycho atoms like Uranium
Renewable: Living Things
Alive Matter: Animals, Humans
Sun/Solar
Wind (Caused by Sun)
Water: Dams (Potential to Kinetic)
Biomass: Burn it! Living Plants
ETSC 101 Chapter 7 Hacker
Less mass, less time, more output, but not renewable
More mass, more time, less output, but renewable
Nothing is for free. Non-renewables took millions of years to form. Renewables take long times to be utilized and don’t output much.
5
Activity
Research the different energy resources, analyzing them in terms of pros and cons (tradeoffs like from week 1) and make an educated guess at to which one will be the major energy resource of the future. (5 min).
ETSC 101 Chapter 7 Hacker
Power Systems
Internal – Small and portable; Less efficient (25-30%).
External – Large and stationary; More efficient (33-48%).
Solar Cells – We are now up to 22% maximum efficiency. Dependent on environment.
Wind Turbine – 15-30% maximum efficiency. Dependent on environment.
Hydro – 90% maximum efficiency. Highly dependent on location.
ETSC 101 Chapter 7 Hacker
Internal: Combustion engine, four stroke Otto cycle.
External: Steam/Nuclear power plant, Rankine cycle.
7
Steam Power Plant
ETSC 101 Chapter 7 Hacker
Determine all of the energy conversions and forms of energy that are present in the Rankine Cycle system. Also describe what is going on (3 min).
Coal, Uranium, or natural gas is usually the fuel to add the heat to the medium (almost always steam). The steam experiences an increase in temperature and pressure, therefore an increase in energy. That energy is used to drive a turbine generating electricity in a generator and also powering a pump to cycles the steam through the condenser to change in back into a liquid and back into the input of the system.
8
Laws of Thermodynamics
Conservation of Energy
With each transformation of energy, there is a net decrease in energy value (entropy).
ETSC 101 Chapter 7 Hacker
Energy isn’t created nor destroyed. Just like with mass.
Energy has value: The more energy is distributed between masses, the less value it has. The concept of entropy is at play here. Entropy is the amount of energy that can no longer do mechanical work, it is a measure of disorder. Everything in the universe is constantly and more and more moving to a state of disorder, lowest energy state, equilibrium, lack of energy gradient. Mechanical work can only be done with energy gradients.
Entropy is the enemy!
9
Activity: Bouncy Balls!
Materials:
12” Ruler
Bouncy ball
Procedure:
Note the initial height (h1).
Drop the ball from h1.
Have on teammate film the drop with their camera, and another visually inspect the drop. Note the final height that the ball bounces up to. Do this 5 times and then take the average. Compare the video values and the teammate observation values. Try a different kind of ball when you are done!
Determine the coefficient of restitution (h2/h1)^.5.
Where did the missing energy go? Can that energy be recovered in anyway? Does the amount of energy loss differ with the kind of bouncy ball used in the testing?
ETSC 101 Chapter 7 Hacker
Mgh1 = mgh2 + W
Coefficient of Restitution = (h2/h1)^.5
Mgh1 = 0.5mv1^2
Mgh2 = 0.5 mv2^2
R = V2/V1
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