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open system
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can gain and lose mass and energy
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closed system
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a system that does not gain nor lose mass
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Isolated system
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a sytem that does not exchange mass nor energy
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impulse (I)
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I or ΔP = FΔt
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impulse unit
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N.s
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Location on a graph
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under the Force - Time curve
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Momentum
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P = mv
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Law of Conservation Of Momentum
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m1v1 + m2v2 = (m1+m2)v
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in any closed or isolated system, the momentum is conserved
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impulse is the change in momentum, so I = ΔP
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KE Formula
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KE = (1/2)mv2
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work-energy theorem
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work is equal to the change in KE ( W = KEf - KEi )
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Gravitational Potential Energy
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energy stored as a result of the gravitational attraction of the earth on the object
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Formula
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PE = mgh
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Elastic Potential Energy
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the energy stored in elastic materials as a result of their stretching or compressing
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Simple Machine
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a machine that makes work easier by changing the value of force or its direction
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compound machine
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a device that uses multiple simple machines
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Mechanical advantage
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Fr / Fe (resistance force / effort force)
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Ideal Mechanical Advantage
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de / dr (effort displacement / resistance displacement)
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Compound Mechanical Advantage
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the product of the MA of its simple machine components
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Efficiency
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(W output / W input) x 100% or (MA / IMA) x 100%
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Types of simple machines
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pulley - lever - wedge - incline plane - screw
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Inelastic collision
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the kinetic energy after the collision is less than it originally was
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elastic collision
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the kinetic energy remains the same after the collision
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super elastic collision
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the kinetic energy increases after the collision
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kinetic energy decreases when the objects stick together
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Work
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the translation of energy in mechanical ways
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Work Formula
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Fdcos(θ)
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Work Unit
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J
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Location on graph
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under the force - displacement curve
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Work done by Friction
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-fk x d
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Work done by Gravity
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mgd
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Work = 0
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when the force is perpendicular to the displacement (90 degrees)
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W is positive
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if the work is done on the system
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W is negative
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if the work is done by the system
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mechanical energy
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the sum of the potential and kinetic energies
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Power
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P = W/t
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Power Unit
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Watt = kg.m2/s3
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