Physics Exam 1
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Energy is defined as?
Capacity to work.
Potential energy is?
- Stored Energy
- ex. Nuclear, Fuels
Kinectic Energy is? Example?
- Energy in Motion.
- Ex. Wind, Riding Bike
Global demand for energy has ______ in the past 50 years and might ______ in the next 30 years.
The first modern oil well was drilled in Pennsylvania in ______
Two approaches to energy conservation?
- Technical Fix
- Ex. More efficient engines
- Lifestyle Change
- ex. Turning down Thermo
Motion is _______ of an object and basic terms associated with it is ______ and ________
- Speed- change of distance
- Velocity-Rate of change
Force causes the _______ of an object to change. The angular counterpart of force is _______.
Rotational motion measures in angular ______ ex.______., Rotational_______ ex.______ and rotational ________
- ex. Degrees and Rads
- Rotational Velocity
- ex. RPM
- Rotational Acceleration
Mass is the measure of an objects _______ to move.
objects SLUGGISHNESS to move
Rotational Mass rule of thumb is, The ______ mass is from center the more sluggish.
- EX. Sphere Vs DISK Vs RING
- SPhere 1st Place
- DISK 2nd
- Ring 3rd
Newtons 1st law of Motion says.....
An object in motion stay in motion( or not in motion) unless acted upon by outside forces!
Newtons 2nd Law of motion says.....
An objects acceleration is directly proportional to the net force acting on it and inversely proportional to its mass.
Newtons 3rd law of motion says...?
- For every action force there is an equal and opposite reaction force.
- i.e. pushing on a wall.
Work is ....?
- Work= Force x Distance
- W=FxD Expressed in Joules
- Ex. Throwin, Running, walking can of coke up stairs
Power is defined as.....?
- Power= Work/Time
- P=W/T Expressed in Watts
- Ex. How Fast I get can of coke up stairs
3 types of Energy Systems
Open=Mass & Energy allowed to flow across
- Closed=Energy allowed to flow
- MASS not allowed
Isolated=No Mass or Energy allowed to flow
Efficiency is defined as....?
- Efficiency=Useful energy output
- Total Energy Input
To Find overall Efficiency....
- multiply the product of individual efficiencies.
- Ex. .35*.9*.05=1.6% overall efficiency
Principle of conservation of energy is stated as...?
- The energy into a system equals to the energy that leaves plus the increase of energy stored in the system.
- Ex. Solar house- Energy coming in is equal to energy leaving plus the energy stored in concrete, walls, floors etc.
What is the energy inputs and outputs of fossil fuel plant?
Inputs: Fuel, air for combustion, Cooling Water(to Condenser)
OutPuts: Electrical Energy, hot water(from condenser), gases through stacks
Rankin cycle is defined as....?
A cycle in which the working fluid changes state.
Example: Steam turbine engine
Gas cycle is defined as...?
A cycle in which the fluid is a gas at every point.
Ex. Internal Combustion Engine
First Law of Thermo's states that.....?
(Hint):Think of Principle of conservation of Energy!!
- work done plus heat added is equal to the change in total energy of the system!
- Remember: q=Heat
Greater Specific Heat=Greater Thermal Storage
Example of Specific Heat?
Phase Change: Latent Heat
- Latent Heat is heat added during phase change
- ***** NO TEMP CHANGE
- ****Graph LEVELS OFF "-------"
Phase Change:Fusion Heat is...?
- Heat added to convert from solid to liquid.
- ****THERE IS TEMP CHANGE
- ***Graph LOOKS LIKE "/?
Phase Change: Heat of Vaporization is...?
- Heat added to convert from liquid at its boiling point to gas
- *****There is Temp Change
- ****Graph looks like this "/"
Conduction is a mode of heat transfer where...?
Heat is transferred through molecular collisions from a hot object to a colder one.
Ex. A spoon handle heating up in pot of boiling water!
The closer objects are in temp the Faster/slower conduction will occur?
Heat Transfer Modes: Convection is...?
- The transfer of heat through a material by the movement of the material.
- Ex: Convection Currents-Hot air rises and replaced by cold air and so on.
Two types of Convection are....?
Natural-Relies on density is less @ higher temp.
Infiltration (homes)- Air leaks through electrical outlets etc.
Moes of Heat Transfer: Radiation is...?
Radiation is the transfer of energy by the emission of electromagnetic waves which carry energy away from emitter.
Ex. Heat exhausted by a hot water radiator.
The higher energy an emitter is the Longer/shorer the wavelength?
The higher energy an emitter is the SHORTER the WAVELENGTH
The 2nd Law of Thermos says...?
- 4 an isolated system Entropy can Increase
- 'Heat can flow spontaneously only from a hot source to a cold sink
- ''No heat engine can be constucted in which heat from hot source is converted entirely to work. Some Work must go to lower colder sink!!! ENTROPY
Entropy and the 2nd law of thermo's says that...
Entropy aka disorder may only increase. Unless there is work put into a system then and only then will entropy decrease.
NEVER have 100% Efficiency unless your Carnot who represents the PERFECT ENGINE calculated by
Question? Using Carnot Equation m=Th-Tc
what is the max efficiency of plant if the temp of the steam is 540'C. The Temp of Cold Reservoir is 20'C.
- 1st: Convert both temps to Kelvin!!!! Must be in Kelvin!!!!
- -540'C = 813'K
- - 20'C= 293'K
- 2nd: Enter Into Equation: 813'K-293'K
- 3rd: Answer is .64 or 64%
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