Properties of Energy
Energy Transformations
Forms of Energy
Energy Math
Miscellaneous
100
True or False: Energy can be transferred from one object or system to another through the interaction of forces between the object.
True
100
What are three ways that energy can be converted through the action of forces?
Energy can be converted when gravity accelerates a falling object, when charged particles are affected by magnetic and electrical fields, and when friction results in thermal energy.
100
How is energy defined?
Energy is the ability to cause change or do work.
100
What information do you need to calculate velocity and what is the unit of measurement?
You need to divide the distance by the time, and the unit of measurement depends on the units for distance and time in the problem. For example, if the distance is in meters and the time in seconds, the unit is m/s. If the distance is in miles and the time in hours, then the unit is m/h or mph.
100
Sound is a form of what type of energy?
Mechanical (vibrating particles transfer energy through matter and there is a constant shift between kinetic and potential energy and particles are compressed and then spread out again)
200
True or False: Energy comes in many forms, but whatever form it takes remains constant and unchanging.
False. Energy can be converted (and usually is) from one form to another.
200
What are the ways energy can be converted when photons are absorbed?
The energy of the photon can increase particle motion converting it to thermal energy, it can be converted to kinetic energy to moved charged particles resulting in electricity, and it can bring about chemical changes.
200
How is chemical energy used to do work?
The chemical bonds in food are broken in our bodies as we respirate. As a result, our muscles have energy to move, and the chemical energy is transformed to kinetic, allowing us to do work and cause change.
200
How is force related to work? What unit is used for work?
Work is calculated by multiplying the amount of force applied across a certain distance to an object. The unit for work is either Newton-meters (a combination of the units for force and distance), or Joules, because one Joule is equal to one Newton-meter.
200
A rainbow is an example of what type of energy?
Electromagnetic (it shows the spectrum of colors in visible light when the waves are refracted by raindrops)
300
Compare nuclear fission and nuclear fusion.
When the nucleus of an atom breaks open, tremendous energy is released. If one nucleus is broken open, we call this fission. When two nuclei come together (releasing the energy from both), this is called nuclear fusion.
300
What is the difference between diffuse and coherent reflection, and will this happen in objects that are transparent?
Photons can either be absorbed, reflected (bounce off), or can pass through a material. If the material is transparent, then the photons are transmitted through. If the material reflecting photons is smooth, it is said to be coherent reflection, and if the surface is rough, it is said to be diffuse reflection.
300
What are the three types of potential energy? Give an example of each.
There is gravitational potential energy which the energy something has based the it's position above a surface and the potential for gravity to pull it down (a book on a shelf). There is chemical energy due to the energy stored in the chemical bonds between atoms and molecules (food). And finally there is elastic potential energy based on how a material stretches (a stretched rubber band).
300
Why does an object higher off the ground have more G.P.E.? Will an object with a greater mass have more G.P.E.?
G.P.E. is calculated by multiplying the weight times the height. So the greater the height, the larger the number being multiplied, and thus more G.P.E. Gravity can more greatly impact a higher object. Weight is determined by multiplying the mass times the rate of acceleration due to gravity, so if mass increases, then so will the weight, and so will the G.P.E.
300
Eventually in Newton's Cradle the balls slow down and stop. Have they lost energy? Has the Law of Conservation of Energy been broken? Explain.
The Law of Conservation of Energy has not been broken. Some of the kinetic energy is transformed to sound energy. In addition, some of the kinetic energy is transformed and "lost" (absorbed by the surrounding air) to thermal energy due to the friction between the balls when energy is transferred and the friction with the air as they swing back and forth.
400
Explain the relationship of work to energy.
The energy of an object or system depends on how work the object or system can do on something else. For example, when we move something (doing work), we transfer our energy to something else, changing its overall energy.
400
Describe the energy transformations of a pole vaulter.
The chemical energy of the athlete is transformed to kinetic when she runs. She transfers some energy to the pole when she digs it into the ground, and the pole has elastic potential energy when it is bent back. Then the potential energy of the pole is transferred to the athlete and she rises into the air "gaining" gravitational potential as she rises and "losing" gravitation potential as she falls (actually the balance of kinetic and potential is constantly changing, while the total mechanical remains fairly constant other that what is "lost" to thermal.
400
What is resistance and how is it related to electrical energy?
Resistance is something that prevents a material from conducting well. When resistance is high, then it is harder for charged particles (electrons to move as current) and back pressure is created which eventually allows a big push of electrons to go through.
400
How are power, work, and energy related?
Energy is the ability to do work or cause change. Work is determined by multiplying force and distance, and the amount of work gives a good indication of the total energy transferred. The amount of power used depends on the rate that energy is transferred or work is done. A faster rate of doing work means more power was used.
400
Why do the balls eventually stop moving in Newton's Cradle is energy is supposed to be conserved?
As the energy is transferred from one ball to another there is friction, causing some energy to be converted to thermal, some of the energy is transformed to mechanical in the form of sound, and there is additional energy transformed to thermal as the balls move through the air and fluid friction is created.
500
Explain the relationship between the Theory of Relativity and First Law of Thermodynamics.
Einstein's Theory of Relativity states that the amount of energy in matter is equal to the mass of the matter multiplied by the speed of light squared (this is a very large number!). The First Law of Thermodynamics says that energy can only be transferred or converted, never lost or newly generated. Einsteins theory tells us that matter is a form of energy, so when energy is released if matter is changed, the energy is not newly created but was actually converted from one form to another.
500
Use the formula E=mc2 to explain how nuclear fusion and fission do not break the law of conservation of energy.
A nuclear reaction releases a huge amount of energy, making it seem as if energy was created. But Einstein determined that there is an enormous amount of energy stored in even the smallest piece of matter, so a nuclear reaction does not break the Law of Conservation of Energy.
500
Mechanical energy is the sum of the potential and kinetic energy of an object. How is this similar to thermal energy How do they differ?
Mechanical energy is the total gravitational potential and kinetic energy of an object. Thermal energy is the total chemical potential and kinetic energy of the particles inside an object. The particles inside of something are always moving to some degree, depending on the type of matter.
500
If the kinetic energy of a 3 Kg baseball was 1,350 J, what would the velocity be?
30 m/s
500
Is the source of energy that heats the center of the earth the same as that which provides us heat from the sun?
Both of these are related to nuclear reactions, but in the sun the reaction is nuclear fusion. Energy is transformed to electromagnetic, which is then converted to thermal when it hits our atmosphere. Below earth's surface, nuclear fission happens when the nucleus of radioactive elements slowly break down over time. Much of the energy released is transformed to thermal energy.
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