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43 Cards in this Set
- Front
- Back
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Work
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when a force is exerted on an object that causes the object to move some distance`
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What are the conditions on work?
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1) Objects must move some distance
2) Objects must move in the direction of the force |
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What does work depend on?
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Work depends on the force applied and the distance the force causes the object to move
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What is the formula for work?
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w=fd
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Power
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the rate at which work is done; the rate at which energy is transformed or transferred
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what is the formula for power?
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p=w/t (p=fd/t)
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What Unit is work measured in?
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Joules (N*m)
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What unit is power measured in?
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Watts (J/s)
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Energy
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the ability to do work
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what unit is energy measured in?
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Joules (N*m)
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What are two main types of energy?)
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Kinetic and Potential
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What are the Forms of Kinetic Energy?
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Mechanical, Thermal, Acoustic, Radiant, Electrical
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What is the formula for KE?
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KE=1/2 * mass * velocity squared
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Mechanical (KE)
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energy an object has b/c of its motion
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Thermal (heat)
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Movement of Particles
-Hotter substances have higher KE than cooler substances (particles move faster in hotter substances) -Temperature |
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Radiant
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energy in the form of ELECTROMAGNETIC waves
-Radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma |
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Electrical (KE)
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Movement of charged particles (electrons)
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Acoustic
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Sound energy produced by vibrating matter
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Mass and KE are _________ ________
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Directly Proportional
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KE is ______ to the square of the velocity
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proportional
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Forms of Potential Energy
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Mechanical, Chemical, Nuclear
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Mechanical (PE)
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energy because of an objects position
-Gravitational or Elastic -Stretched rubber band, bow, compressed spring, any object lifted off the ground wind up toys |
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Chemical
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energy stored in chemical bonds of a molecule
-Fossil fuels, wood, food, battery and your body |
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Nuclear
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energy contained in the nucleus of an atom released by fission or fusion
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Formula for GPE
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GPE=m*g*h
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Gravitational Potential Energy=
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work done against gravity in lifting it
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What does GPE Depend on?
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height and weight
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Law of Conservation of Energy
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Energy can not be created or destroyed; it may be transformed from one form to another or transferred from one object to another, but the total amount of energy NEVER changes
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Formula for the Law of Conservation of Energy
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Total Energy = Potential Energy + Kinetic Energy ( TE = PE + KE)
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Energy can be lost to ___________ or ___ _________ as heat energy, mechanical energy and acoustic energy.
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Friction, Air resistance
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To change the KE of an object ____ must be done
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Work
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The change in KE is equal to the ____ done
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Work
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Work =
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Change in KE
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Work =
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Change in GPE
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3 ways machines "Make work Easier"
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1) Multiply force (Increase input force)
2) Multiply Distance (increase input distance) 3) Change the direction of the force |
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Machines _________ reduce the amount of work done, they actually _____ the amount of work being done (friction)
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Do Not, increase
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What are the six simple machines?
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wedge, pulley, lever, screw, incline plane, and wheel and axle
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If a machine ___________ your force it will ___________ your distance by an equal ratio.
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Increases, decrease
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What is the formula for the Machine Trade-off?
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work (in)= work (out)
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If a machine ________ the distance or speed it will __________ your force by an equal ratio.
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Increases, decrease
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Efficiency
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compares the output work to the input work
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Formula for efficiency
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E=Output Work/Input Work * 100
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Efficiency is ALWAYS <100% b/c work is always lost to ________ within a real system
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Friction
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