Unit B Energy Flow in Technological Systems : Section 2.0 Flashcards
What did early alchemists try to make gold from?
Earth, Air, Water, Fire
How did the science of chemistry begin?
Alchemists learned that by mixing certain chemicals they could produce surprising results
What happens when wood burns?
The energy in the cellulose molecules is released, turning to heat
What is chemical energy?
The potential energy stored in the chemical bonds of compounds
What is Electrical energy?
The work done by moving charges
What is a Volta pile?
A battery made by stacked layers of 2 different metals such as copper or silver with moistened paper between each layer. A wire is connected from the top and bottom layer.
Who created the Volta pile?
Alessandro Volta
What does the volta pile demonstrate in terms of energy?
A connection between chemical energy and electrical energy
What does an electrical current make?
A magnetic field
How does an electric generator work?
By moving a magnet through a coil of wire
Why does a compass get deflected when an electric current is produced?
Because an electric current produces a magnetic field
What shows that electricity can produce magnetism?
When a compass is near an electric current the compass becomes deflected due to the magnetic field produced
What is evidence that heat energy can be converted into electricity?
When a metal circuit is heated it produced an electric current which caused a compass to be deflected.
What is nuclear energy?
The potential energy stored in the nucleus of an atom. This has to do with forming and breaking atoms by altering the amount of protons in the nucleus. Nuclear decay, nuclear fusion (combining), and nuclear fission (separating) can all produce nuclear energy.
How was nuclear energy discovered?
A scientist observed atoms spontaneously disintegrating and they emitted radiation or radiant energy
What is nuclear fission?
When the nucleus of an atom is split and energy is released
What is nuclear fusion?
When the nuclei of 2 atoms join and release energy
What did scientists use to think that the sun’s energy came from?
They thought it was from chemical burning. But then they realized it would take 5 thousand years for all the energy to be used up
What is solar energy?
A type of energy hydrogen-hydrogen nuclear fusion reaction with the release of nuclear energy
The atoms should be combine to make more complex atoms
How does the suns energy travel to Earth?
As electromagnetic radiation and is converted to other forms of energy such as heat
What do all objects in motion share?
Kinetic energy
What is gravitational potential energy?
An object raised above the Earths surface that has the potential to do work
What is mechanical energy?
The sum of energy of motion and position
What is kinetic energy?
Any object in motion made to do work because of its motion
What did scientists originally believe that heat was?
Heat was an invisible fluid called caloric fluid which flows naturally from hot things to cold things
What is thermodynamics?
The science of dealing with the study of the inter-relationships of heat, work, and energy.
What do current scientists believe about heat?
The movement of atoms within a substance determines the thermal energy of the substance.
What is heat?
The transfer of thermal energy from a hot object to a cold object
How are heat and mechanical energy related?
Mechanical energy produces heat energy
Explain Joule’s experiments with the rotating paddles.
James Joule invented a device that can measure the change in temperature of a volume of fluid(heat) per input work (mechanical energy). The main pieces of the apparatus includea thermometer, a chamber for fluid, a propeller submerged in the fluid and a crank for the input work (external).
Joule’s experiment consisted ofa brass paddle wheel stirring water in a copper vessel. The paddle wheel was turned by falling weights possessing mechanical, or kinetic, energy as they fell. The temperature of the water rose by an amount that depended on how far the weights fell.
-When the weights connecting to the rotating paddles fall they lose gravitational potential energy and the paddle has work done to it so it gains the energy in the form of kinetic energy. The kinetic energy transforms into heat.
Explain Joule’s experiment with the wooden block.
The wooden block that is falling has kinetic energy until it collides with the other block where it loses its kinetic energy since the kinetic energy is transformed into heat energy.
What are the types of potential energy?
- Chemical energy
- Gravitational energy
- Nuclear energy
- Elastic energy
What is mass?
- A scalar quantity measured in kilograms
- Never changes
What is weight?
A vector quantity that measures the force of gravitational attraction on an object in Newtons.
Weight is mass times the acceleration due to gravity. The acceleration due to gravity changes depending on what celestial body you are on.
What does the weight of an object depend on?
The acceleration due to gravity
What is the formula for weight?
Weight = mg
What is elastic potential energy?
When a force is used to stretch an elastic so that it stores energy
When is potential energy useful?
When it is converted into another type of energy
Describe how chemical potential energy works?
- Energy stored in bonds of chemical compounds
- a chemical reaction takes place and positions of electric charges are altered and energy is released
Where does the word kinetic come from?
The greek word kinema which means motion
What are the types of kinetic energy?
- Electrical energy
- Magnetic energy
- Radiant energy
- Heat energy
- mechanical energy in some cases (since mechanical is a combination of kinetic and potential energy)
What is mechanical energy?
Kinetic energy and potential energy combined
What is the law of conservation of energy?
The total amount of energy in a situation remains constant. energy can be converted from one form to another.
What are the three pieces of evidence for energy change?
- Motion or change in position
- Change in shape
- Change in temperature
What are the most common energy conversions in the natural world?
- Nuclear fusion (joining of atoms to create atoms with higher amounts of protons and thus different elements) in the sun converts chemical potential energy into kinetic energy in the form of electromagnetic waves
- Photosynthesis: when light strikes plants a chemical reaction converts carbon dioxide and water into glucose and oxygen. The glucose is chemical potential energy so when animals eat the plants the chemical potential energy is released as carbon dioxide but along with this kinetic energy is possible (the animals have energy to move)
What are hydro-electric dams?
A system that converts the energy of moving water into electricity
How does a hydro-electric dam work?
- Water is stored up high and posseses gravitational potential energy
- As water falls the gravitational energy converts to kinetic energy
- When the water reaches the turbines its kinetic energy turns the turbine
- The turbines turn a coil of water in a magnetic field and converts the kinetic energy in into electrical kinetic energy
How does a coal-burning power station work?
- Coal is burned and the chemical potential energy is converted into kinetic heat energy
- The kinetic heat is used to warm the water in a boiler to steam
- The steam’s kinetic energy is ejected into the turbines causing them to rotate
- The kinetic energy from the steam then moves the turbine which converts into electrical energy.
In nuclear energy reactions do they use fission or fusion?
Fission
How do nuclear reactors work?
- Uranium disintegrates during nuclear fission releasing nuclear potential energy
- The potential energy converts into radiation kinetic energy
- The radiation is converted into thermal energy which is used to heat water to steam
- The steam is used to turn turbines
- The turbines turn a coil of wire in a magnetic field which then the kinetic energy is turned into potential energy
What is different about solar cells compared to other methods of generating power?
They have no moving parts, only the charges move
What is a photovoltaic cell composed of?
Photovoltaic panels are installed for the conversion of thermal energy into electricity, while solar panels convert solar radiation into heat
Two layers of silicon (Si) one with phosphorus (P) and one with boron (B)
Silicon is abundantly available, making it the second most available element on Earth (main component of sand).
The most common material for commercial solar cell construction isSilicon (Si), but others include Gallium Arsenide (GaAs), Cadmium Telluride (CdTe) and Copper Indium Gallium Selenide (CIGS).
How does a solar cell work?
- When sunlight hits the layers it provides energy for one to become positive and one to become negative (boron for one and phosphorus for the other, both have silicone)
- The cells act as a battery and electric current flows
How do fuel cells work?
They convert chemical potential energy from hydrogen into electrical energy and the cells do not require charging as long as they have the fuel. Hydrogen and oxygen chemically react to produce electricity.
What is kinetic energy?
Energy due to movement
What is potential energy?
Energy that is stored and held in readiness and has the potential to do work
