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50 Cards in this Set
- Front
- Back
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Simple Machines
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- comprise most mechanisms
- redirect energy - manipulate force, distance, and speed |
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Mechanical Aadvantage
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- MA=Resistance Force / Effort Force
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Levers
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- 1st Class: E F R (forces is same direction)
- 2nd Class: E R F (forces in opposite direction) MA>1 - 3rd Class: R E F (forces in opposite direction) MA<1 |
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Moment
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M= Force * Distance
Equilibrium: E*Le = R*Lr |
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Wheel and Axle IMA
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IMA = De / Dr
MA = R / E |
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Pulley
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- used to change direction and magnitude of force
MA = # of strands (only count last strand if it points up) AMA = Fr/ Fe |
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Gear Ratios
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- change speed of rotation, direction of rotation, amount of torque
GR = Nout / Nin = Dout / Din = Win / Wout = Tout / Tin GR=gear ratio N=number of teeth D=diameter W=angular velocity T=torque |
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Inclined Plane
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IMA = De / Dr
IMA = length / height |
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Wedge IMA
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IMA = De / Dr
IMA = L / T |
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Screw IMA
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IMA = De / Dr
De = 1 rotation of effort arm = circumference Dr = linear distance traveled during rotation of the effort arm = pitch IMA = circumference / pitch = 2piRe / P |
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Energy Sources
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- energy is ability to do work
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Nonrenewable Energy Sources
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- fossil fuels
- uranium |
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Renewable Energy Sources
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- animal
- food - biomass |
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Inexhaustible Energy Sources
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- hydroelectric
- tidal - wind - solar |
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Work
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W = force * distance
joule is base unit = 1 newton * 1 meter |
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Power
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rate at which work is performed or energy is expended
P = work / time watt is base unit of power 1 watt = 1 joule |
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Mechanical Winch
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power output = work / time
Power input = voltage * current Efficiency = (Pout / Pin)*100 |
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Conservation of Energy
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energy cannot be created or destroyed
can change one form to another |
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Energy Conversion
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changing one form of energy to another
Efficiency = useful energy : energy supplied Entropy = loss of energy during conversion |
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Electrical Circuit
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system of conductors and components forming a complete path for current to travel
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Voltage
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force (pressure) that caused current to flow
measured in volts (v) |
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Current
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flow of electric charge
measured in amps (A) |
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Resistance
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opposition of current flow
measured in ohms |
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Ohms Law
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V=IR
V- voltage I - current R - resistance |
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Series Circuits
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components are connected end-to-end
single path for current to flow |
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Parallel Circuits
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both ends of components are connected together
multiple paths for current to flow |
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Series Formulas
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current same everywhere
resistance adds to total voltage adds to total |
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Parallel Formulas
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voltage same everywhere
current adds to total total resistance is equal to reciprocal of sum of reciprocal |
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Hydrogen Fuel Cell
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creates electricity and heat through electrochemical process that converts hydrogen and oxygen to water
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Thermodynamics
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study of effects of work, heat flow, and energy on a system
movement of thermal energy |
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Thermal Energy (heat) Transfer
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transfer of movement of thermal energy
100% efficiency unattainable |
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Convection
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movement of air
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Conduction
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movement through an object through touching
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Radiation
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electromagnetic waves
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Calculating Energy Transfer
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Q = U * A * change in temp
Q = energy transfer U = U value A = area U value = 1 / R value |
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Design Process
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systematic problem solving strategy
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Design Brief
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defines a problem
concise document identifies client states client's problem lists specs lists constraints |
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Design Team
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collection of individuals
each with own expertise brought together to benefit common goal |
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Define A Problem
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Receive a problem to solve from client
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brainstorm
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generate and record ideas
develop preliminary ideas based on constraints |
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generate and research ideas
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conduct interviews
generate and compile ideas |
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identify criteria and specific constraints
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identify constraints
draft design brief |
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explore possibilities
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consider further development of brainstorming
explore alternative ideas |
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select and approach
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use decision matrix
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develop a design proposal
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explore idea in greater detail
sketch or model |
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make a model or prototype
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build
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test and evaluate the design using specs
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trial runs
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refine the design
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modify design
rebuild prototype |
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create solution
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final design
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communicate processes and results
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media (Powerpoint)
poster market product distribute |
