Energy und Heat Transfer Flashcards
Energy is…
The ability to do work.
What are the 8 energy stores?
Kinetic, magnetic, nuclear, gravitational, elastic, chemical, electrostatic and thermal.
What are the 4 kinds of energy pathways?
Heating, radiation, electrical and mechanical.
What is the law of conservation of energy?
Total energy before transfer = total energy after transfer.
What is the unit for energy?
Joules.
What is the most commonly used unit for energy in food?
Calories.
What are fossil fuels?
Fossil fuels are non-renewable energy resources made of fossils of plants and animals.
What are the three types of fossil fuels?
Coal, oil and gas.
How is coal formed?
Some dead plants millions of years ago fell into swamps. The mud and water stopped the plants decaying and they slowly get covered with sediment. The heat and pressure turn the plants into coal.
What are the main kinds of renewable energy?
Solar (thermal or photovoltaic), geothermal, biomass, tidal, wind, hydroelectric and waves.
What are the 5 questions you need to ask to see if an energy resource’s advantages?
Is it reliable? Does it release air pollution? Does it need a fuel? Does it have any effects on local habitats/ecosystems? Does it need a special location?
What is heat transfer?
It is when heat from a hot object gets transferred to a colder object.
How is temperature determined?
It is the average of the kinetic energy store in the particles of an object.
What are the two things that determine the temperature?
The size and heat of an object.
What are the 3 types of heat transfer?
Conduction, convection and radiation.
How is heat transferred in non-metal solids?
Atoms near the heat source begin to vibrate. These vibrations make adjacent atoms vibrate.
Why are metals good conductors?
Because they have many free electrons that carry energy from high energy atoms to low energy ones.
Density=
Mass/Volume
A increase in volume=
A decrease in density.
When a substance becomes less dense, do the atoms get larger?
No, the gaps between atoms get bigger.
How are convection currents formed?
When a heat source is placed in an area filled with fluids.
How do convection currents work?
Air near a heat source heats up and becomes less dense. The hot air rises. To fill in the vacuum near the heat source, the colder, more dense air which is far from the heat source sinks to near the heat source. The cold air gets heated up and the cycle repeats, causing a convection current.
What is unique about radiation?
It travels via waves, not particle.
What kind of material is the best radiator?
Matt black.
