Transformation of Energy: Difference between revisions
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==The Main Idea== | ==The Main Idea== | ||
Energy Transformation is the process in which energy changes from one form | Energy Transformation is the process in which energy changes from one form to another. Examples of forms of energy include: Kinetic, Chemical, Thermal, Potential etc. Whenever energy changes its form, there is no net loss of energy (Conservation of Energy). Virtually every process we engage in is accompanied by a transformation of energy. Some common everyday examples of energy transformation include, the chemical energy of coal being converted to thermal energy when burned, or the conversion of electromagnetic energy from the sun into chemical energy in plants. | ||
It is important to account for the efficiency of an energy transformation. Every energy transformation is accompanied by some change in thermal energy. In other words, it is not possible to convert 100 J of chemical energy to 100 J of kinetic energy; some of the chemical energy will be converted to thermal energy. This is usually due to friction. [[File:EnergyTransformation.gif|thumb|300px|right|Energy Transformation in Energy Systems]] | |||
In the figure on the right, there is a candle being burned. When something is burned, the energy stored within the chemical bonds that hold the object together are broken and energy is released. In the figure, the chemical energy of the candle is being converted into both Heat and light. Practically, it would be much more useful if 100% of the chemical energy of the candle was converted into light (the purpose of a candle). If this were the case, either the candle would burn much brighter, or burn longer, since energy is no longer being wasted as Heat. As stated above however, this process is not 100% efficient; Thus, some energy will inevitably be converted into Heat energy. | |||
=== | ===Mathematical Model=== | ||
If we assume | If we assume a system has energy <math>E_{0}</math> initially, no energy is being converted to work, and no energy energy is being lost or added as Heat, then we can simply say: | ||
= | ::<math>E_{0} = E_{f}</math>, where | ||
:::<math>E_{f} =</math> the final energy of the system | |||
Note that <math>E_{0}</math> and <math>E _{f}</math> don't specify what form the energy takes, merely that their values are equal in Joules when summed. The energy could be transformed in a myriad of ways that are consistent with the above equation. | |||
===Computational Model=== | |||
:'''Insert Computational Model here''' | |||
The VPython model below demonstrates a space probe orbiting the Earth and Moon. The probe is under the influence of the Earth's gravity and the Moon's gravity. The probe has its own initial velocity. | |||
The graph illustrates the conservation of energy of this system. The yellow curve represents the kinetic energy of the space probe, the blue curve shows the gravitational potential energy of the space probe in orbit, and the green line represents the sum of the kinetic and potential energies. Notice the green line is always the same value... a negative value, meaning the space probe is locked into orbit around the Earth and Moon for now. | |||
[[File:Pythonzzz.png|800px|center|Computer Model]] | |||
In a more realistic model, some energy would be lost as Heat over time. | |||
==Examples== | ==Examples== | ||
Revision as of 12:38, 6 August 2019
Main Idea
Mathematical Model
Computational Model
Examples
Simple
Middling
Difficult
Connectedness
History
See also
Further reading
External links
References
The Main Idea
Energy Transformation is the process in which energy changes from one form to another. Examples of forms of energy include: Kinetic, Chemical, Thermal, Potential etc. Whenever energy changes its form, there is no net loss of energy (Conservation of Energy). Virtually every process we engage in is accompanied by a transformation of energy. Some common everyday examples of energy transformation include, the chemical energy of coal being converted to thermal energy when burned, or the conversion of electromagnetic energy from the sun into chemical energy in plants.
It is important to account for the efficiency of an energy transformation. Every energy transformation is accompanied by some change in thermal energy. In other words, it is not possible to convert 100 J of chemical energy to 100 J of kinetic energy; some of the chemical energy will be converted to thermal energy. This is usually due to friction.
In the figure on the right, there is a candle being burned. When something is burned, the energy stored within the chemical bonds that hold the object together are broken and energy is released. In the figure, the chemical energy of the candle is being converted into both Heat and light. Practically, it would be much more useful if 100% of the chemical energy of the candle was converted into light (the purpose of a candle). If this were the case, either the candle would burn much brighter, or burn longer, since energy is no longer being wasted as Heat. As stated above however, this process is not 100% efficient; Thus, some energy will inevitably be converted into Heat energy.
Mathematical Model
If we assume a system has energy [math]\displaystyle{ E_{0} }[/math] initially, no energy is being converted to work, and no energy energy is being lost or added as Heat, then we can simply say:
- [math]\displaystyle{ E_{0} = E_{f} }[/math], where
- [math]\displaystyle{ E_{f} = }[/math] the final energy of the system
Note that [math]\displaystyle{ E_{0} }[/math] and [math]\displaystyle{ E _{f} }[/math] don't specify what form the energy takes, merely that their values are equal in Joules when summed. The energy could be transformed in a myriad of ways that are consistent with the above equation.
Computational Model
- Insert Computational Model here
The VPython model below demonstrates a space probe orbiting the Earth and Moon. The probe is under the influence of the Earth's gravity and the Moon's gravity. The probe has its own initial velocity.
The graph illustrates the conservation of energy of this system. The yellow curve represents the kinetic energy of the space probe, the blue curve shows the gravitational potential energy of the space probe in orbit, and the green line represents the sum of the kinetic and potential energies. Notice the green line is always the same value... a negative value, meaning the space probe is locked into orbit around the Earth and Moon for now.
In a more realistic model, some energy would be lost as Heat over time.
Examples
Be sure to show all steps in your solution and include diagrams whenever possible
Simple
A candle has 500 J of chemical energy stored in it's wick. After some time, when the entire candle is burned and all the chemical energy is expended,it is found that the candle released 480 J of heat energy. Assuming that the candle only released heat and light energy when it was burned,how much light energy was released by the candle when it was burned?
Since the candle is completely burned, all its chemical energy is completely converted. The problem states that all this energy is converted to either heat or light energy. It is also stated that 480 J of heat energy was released. Therefore, we can write the equation
J chemical energy = J heat energy + J light energy
Thus, 500 = 480 + J light energy
So J light energy = 20 J
Middling
When a person runs a conversion of energy takes place. In this example, use the earth and the person as the system. Write an equation that actually depicts the change in energy of the person and earth system as the person runs down a slope . Assume that the only forms of energy in this equation are gravitational potential, chemical energy, heat, and kinetic energy.
Since humans utilize energy in the form of chemical energy, we start off with a change in chemical energy. When the person accelerates and begins to run, some of the internal chemical energy is converted into kinetic energy. Remember from above that in any change in energy form, some thermal energy is also produced. Notice however, that the person is also running down a slope. This means that the gravitational potential energy between the earth and the person is decreasing. But what is this energy being converted to? The gravitational energy is most likely not forming new chemical bonds in the person's body so it's not chemical energy. It is however possible that this gravitational energy is being converted to kinetic energy, and of course, heat. So we have two sources of kinetic energy, the person converting chemical energy into kinetic energy as well as the earth "pulling the person" downhill increasing his kinetic energy.
We can then write our equation as E chemical + E potential = E kinetic (From chemical) + E kinetic (from gravity) + E heat
Difficult
A water heater is created to heat water for the purpose of turning a turbine. 20 kg of Water at 25 degrees C is heated and forced to evaporate at 100 C per second. Assume the specific heat of water varies little with temperature. This process takes place at 1 atm. This heat energy is being supplied by a stirrer in which 70% of it's kinetic energy is transferred to heat energy per second. Assuming this process is continuous, with 0 accumulation, how much energy must the stirrer transfer to the water per second to achieve this? Assume the process takes place in an adiabatic closed system with a constant volume and pressure.
For this problem we must first determine how much heat is required to evaporate the water, and then heat it to 300 degrees C . The easiest way to do this is using our q = cm delta t equation. First, we heat the water from 25 degrees C to 100 degrees C. This equation becomes --> q = (4.18 kj/kg*C)(20 kg)(100-25 C). We are left with q = 6270 kJ. Now, we need to determine the heat required to convert the water from liquid to a gas. This is also known as the heat of vaporization which is 2257 kj/kg. We can then say q = (2257 kj/kg)(20)Kg we get q = 45,140 kj. Thus, the total heat energy required to raise the water from 25 C to 100 C and then evaporate it is 6270 kj + 45,140 kj = 51,410 kj.
Since the turbine operates at 70% efficiency, we know it must generate more energy than the heat we just found previously. We can simply divide 51,410 by .7 to get 644,871.4 kj. The turbine must generate 644,871.4 kj per second or 644,871 KW.
Connectedness
I am currently very interested in oil refinery and as a chemical engineer, I hope to some day work in this sector. Oil is probably one of the most converted energy sources in the world. The whole point of refinery is to extract the maximum amount of usable energy from the chemical bonds of oil. This is accomplished through the use of changing parameters such as pressure, temperature, volume etc. This is directly applicable to energy transformation since the whole point of this process is to use what we know about the properties of oil and make energy efficiency as close to 100% as possible.
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History
Energy has been converted through forms since the beginning of time with the big bang, and the formation of the first stars. Humans themselves are constantly converting chemical energy into kinetic energy as we go about our daily lives. It can be argued that transformation of energy really began happening on a large scale with the entrance of the Industrial Revolution in the late 1700s. At this point in time, the chemical energy in coal was being converted to thermal energy to heat up water, which was then used to turn turbines and generate usable energy. Today, energy conversion is all around us. Perhaps the most common form of energy transformation is electrical energy. A myriad of appliances exist that can convert electrical energy into any form of energy depending on what type of energy is required that situation.
See also
Are there related topics or categories in this wiki resource for the curious reader to explore? How does this topic fit into that context?
Further reading
"Battery and Energy Technologies." Electricity Generation Using Steam Turbines. Web. 4 Dec. 2015.
This is an interesting article on how a steam turbine works by converting thermal energy to kinetic energy.
External links
http://www.nsta.org/publications/news/story.aspx?id=51729
This is an article which describes how the human body turns energy from food molecules into useful energy.
References
I used mostly the textbook for this assignment.
Chabay, Ruth W. Matter and Interactions. 3rd ed. Hoboken, N.J.: Wiley ;, 2010. Print. Pictures from: http://ndstudies.gov/energy/level2/files/level2/img/module02/distillation-tower-illustration.jpg
