Inceased use of fossil fuels since the beginning of the industrial age hasincreased the carbondioxide concentration in the atmosphere by____ and has increased the earths temp.
35%
in 2009 what % of energy consumption in the US was provided by renewables
5%
Global demand for energy has ___ over the past 50 years and might ___ in the next 30
tripled, doubled
when ws the steam engine invented?
1763
The US consumes ____ times the worlds avg. energy per capita.
5
Conservation technologies can be put to use more quickly than we can increase supplies. For example, it takes _____ years to contruct a nuclear power plan but conservation practice can begine immediatley because the technology is available and simple
9 to11
The chemical energy stored within oil may be considered as ____ associated with molecular bonds, which are changed or broken during combustion
Potential Energy
What is the type energy associated with an objects motion
kinetic
The SI unit for force is
NEwton
In the equation for work, it is important that the force is applied?
in the direction of the motion
__ is the rate of doing work
Power
F=MA is a statement of which of newtons laws of motion
Second Law of Motion
_____ is the tendency of all objects to resist changes in their motion
inertia
T or F. In an isolated system the cahnge in the total energy will always be zero
True
T or F. Energy conservation and conservation of energy are really a statement of the same thing?
False
In fossil Fuel power plant which are energy inputs?
Air into boiler, Cooling water to condenser, Fuel into boiler
In a multistep process the overall efficiency is equal to the____ of the individual efficiencies.
Product
What is the typical efficiency of a fossil fueled power plant
35%
When talking about energy quantities of various fuels it is best to speak in terms of >
Heating Value
Which is a larger amount of energy. 1 Btu or 1 calorie.
1 btu
buildings account for ____ of the elctricity use in US
70%
Heat is_____
The energy transferred between bodies due to a temp difference
A heat engine...
converts heat energy into mechanical energy
The quantity of heat that must be added per unit mass at the solids melting point to convert it entirely to a liquid at the same temperature is call the _____ of the material
heat of fusion
As liquid changes into a vapor
Heat energy is being absorbed
A hot object with a high specific heat cools down more quickly than an objec with a low specific heat T or F
False
Why does carpet feel warmer than tile?
Tile has a higher thermal Conductivity therefore can conduct the heat from foot more effectively
Draw a phase change diagram>>> Include Temp, Heat input, Tmelt, Tboil, Solid, Liquid, Gas
Difference between heat and temp?
Heat is the flow of energy from one body to another due to temp difference.
Temp is the measure of the kinetic energy of molecules in material
Explain why transformers only work with Ac.
Include 2nd connection of magnet and electricity.
Based on 2nd connection between electric/magnet. A changing magnetic field excites the flow of electrons.
Therefore the only way 2 induce the flow of electrcity in the 2nd coil is for the iron core 2 have a changing field only accomplished by AC
Why do we transmit electricity over our electric grid w/ac @ high voltages
Transmission is all about minimizing power loss in transit.
Power is proportional 2 current. We must minimize current to minimize power loss. This can be done by switching voltage for current which is accomplished through a transformer and that only works by ac .
Thermohaline circulation derived from two words.
Thermo=HEat
Haline=Salinity
V=IR is statement to whos law
Ohms
As more devices are added to a series circuit the current or resistance increases
True
Heat transferred through fluids primarily by the motion of the gas or liquid is called
convections
Heat transfer by radiation requires a medium with a high specific heat value T or F
False
All types of electromagnetic radiation have the same velocity in a vacuum
True
Hotter objects emit EM radiation with a wavelength that is ____ than cooler objects
Shorter
A heat engine_____
Needs a temperature difference to be able to work
A cycle in which the working fluid changes state is called a
Rankine Cycle
The maximum efficiency of a heat engine operating between 2 degrees C and 200 degrees C will be about___
