What kind of energy does a skier have at the top of a hill?
Potential energy due to gravity
100
In which form does most useful energy on Earth begin?
electromagnetic energy from the Sun
100
What does the law of conservation of energy state?
Energy is neither created nor destroyed.
100
In many common energy conversions, most of the wasted energy is released as what?
heat
100
Where does most energy used on Earth come from?
fossil fuels
200
What is the source of potential energy in a hydroelectric dam?
water held behind the dam
200
Name one energy conversion that takes place when striking a match.
chemical to thermal, thermal to light, chemical to kinetic
200
Kinetic energy is converted into which two forms after a ball is kicked?
heat and sound
200
What does LED stand for?
light-emitting diode
200
What are two advantages to using solar and wind energy?
unlimited supply and clean sources of energy
300
What energy conversion takes place when the dam's wall is opened?
potential energy is converted to kinetic energy
300
What type of energy conversion takes place when the turbine in a hydroelectric dam spins?
mechanical to electrical
300
What is the measurement of usable energy after an energy conversion?
energy efficiency
300
Name one way in which cars have become more efficient.
Fuel injectors monitor how much fuel enters the engine, and hybrid cars use electrical energy and stored chemical energy from fossil fuels.
300
What are two ways we use solar energy?
We convert solar energy into electricity and use radiation to heat buildings.
400
How might a skier at the bottom of the hill regain his potential energy?
take the ski lift back up to the top of the hill
400
Why is the Hoover Dam so useful?
It produces a large amount of electrical energy for California, Nevada, and Arizona.
400
Why is energy efficiency important?
Energy efficient appliances use less electrical energy.
400
Name 5 different uses for LEDs.
television remote controls, computer displays, outdoor signs, giant video boards in stadiums, traffic signals, fiber optic cables
400
Why might so many windmills be needed at a windfarm?
They need to capture as much energy from the wind as possible.
500
How is the burning of fossil fuels in power plants different than the burning of fossil fuels at home?
Power plants convert the stored chemical energy into electrical energy, but homes convert the stored chemical energy into thermal energy.
500
Explain 4 different energy conversions that take place when a match is lit.
Electromagnetic energy from the Sun --> chemical energy in plants --> mechanical energy to move the strike the match on the rough surface --> thermal energy to release chemical energy --> electromagnetic energy (visible light) and heat
500
Why can't we develop appliances that are 100% efficient?
There will always be some energy converted to thermal energy due to friction.
500
Name two ways in which hybrid cars make energy conversions more efficient.
They use electrical energy and gasoline to generate kinetic energy, which makes them more fuel efficient. Some kinetic energy lost in braking the car is converted back into electrical energy to recharge the battery.
500
Name three advances we have made in using wind energy.
We have built windfarms in rural areas that receive constant amounts of wind. We have designed special-shaped blades.
We have used more flexible materials in the blades.