Show:
Here Comes the Sun
Out of Gas
Energizer Bunny
Call a Mechanic
Work it Out
100
Commercial ones of these are around 20% efficient.
What is a solar or photovoltaic cell?
100
Energy from earth’s molten core.
What is geothermal energy?
100
This form of energy may make you hot around the collar.
What is thermal energy?
100
This type of motion moves back and forth.
What is reciprocating motion?
100
5N of force used to move an object 4m.
What is 20 Joules of work?
200
The photovoltaic cell on a solar panel converts sunlight into this type of current which must be modified before home use.
What is direct current (D.C.)?
200
This device developed in Egypt about 12,000 years ago was one of the first to harness energy from renewable wind energy.
What is the sail?
200
Benjamin Franklin experimented with this form of energy and found it shocking.
What is electrical energy?
200
If you have used a pry bar then you have used one of these.
What is a lever?
200
6000 watts used for 1 hr.
What is 6 kilowatt hours?
300
A Trombe wall.
What is a device used for indirect gain solar heating?
300
No fossil fuel is used in this renewable method of generating electricity, but you may get wet.
What is hydroelectric generation?
300
Form of energy used by a water wheel.
What is mechanical energy?
300
An offset pivot point characterizes this mechanical device which converts a rotating input to a reciprocating output.
What is a cam?
300
5Amps of current flowing in a circuit driven by 12 Volts.
What is 60Watts?
400
If you plan on using your solar electric energy system to power all of your household appliances, you’ll need to install one of these.
What is an inverter?
400
A Savonius rotor is an example of this type of wind turbine.
What is a vertical shaft turbine?
400
Solar energy starts out as this form of energy in the sun.
What is nuclear energy?
400
This device uses the fact that liquids do not easily compress to change the direction, distance or magnitude of a force.
What is a hydraulic piston?
400
48J of work done by this force being applied for 2m, or 2 dozen fig-flavored cookies.
What is 24N?
500
Considering the advantages and disadvantages of solar electricity generation, why do you think solar energy has not become more widely utilized in the United States?
Solar energy offers a clean, inexhaustible supply of energy for powering our homes and businesses. People may be reluctant to switch to solar energy because they are reluctant to incur the high cost associated with initially installing and operating the devices, or they might be unsure whether they will have sufficient power on cloudy days. They may not like the idea of a large area of the roof having solar panels. With conventional fossil fuel energy prices relatively low, they might be reluctant to change for the promise of a future benefit.
500
Which form of renewable energy do you think will be most important in the future? Why?
Solar electric energy is perhaps the most important renewable energy technology for our future. It is clean and inexhaustible and solar electric devices have no moving parts to wear out. Not all locations have available wind sources, and wind turbines are large and more costly. Biomass resources are renewable, but still require combustion of fuel which emits pollution.
500
What could be done to make people less afraid of nuclear energy technology?
To be less afraid of nuclear energy technology, people would need to be educated concerning the safety and reliability used by nuclear energy plants. They would need to be assured that disposal of material would not be an environmental hazard and assured that safety systems for the safe operation of the plant could account for complex worst case scenarios. Future advancements in nuclear energy technology which are safer or produce less waste might make people less afraid of using this technology.
500
What does the 2nd law of thermodynamics imply for mechanical systems?
One way to state the 2nd law of thermodynamics is that it is impossible to build an engine to perform work that does not exhaust thermal energy to the surroundings. For mechanical systems this means that energy cannot be completely transferred between parts of the system and some energy will always be lost to heat or friction, or some other inefficiency. Attempts at perpetual motion machines will always fail.
500
You stand perfectly still holding a 10kg bag of groceries at arm’s length. Your arms soon become tired, but is work being done on the bag? Explain.
The definition of work is that a force is applied through a distance. Your arms are applying a force, however the load is not being moved through a distance (you are perfectly still), and so technically speaking no work is done on the bag.