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Published byDoreen May Modified over 8 years ago
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Work and Energy Physics 1
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The Purpose of a Force The application of a force on an object is done with the goal of changing the motion of the object.
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Accomplishment of Forces A force (F) will achieve a change in motion when it: acts in the direction of motion change. OR has a component in the direction of motion change.
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Accomplishment of Forces
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Definition of Work The product of the displacement and the force component acting in the direction of displacement is called work.
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Definition of Work When a force F is applied to an object of mass m, the object accelerates from an initial velocity v i to a final velocity v f.
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Definition of Work If the object is displaced d, the work W done by the force F is:
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Definition of Work From
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Definition of Work The quantity of mechanical work produced by an accelerating force was defined as.
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Kinetic Energy Eventually this quantity of mechanical work became known as kinetic energy (KE ). Today kinetic energy is defined as the energy an object possesses due to its motion.
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Work-Energy Theorem The amount of mechanical work done to accelerate an object is equal to the change in the object’s kinetic energy. This is called the work-energy theorem.
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Potential Energy When work is done a resistive force, potential energy (PE) is created equal in magnitude to the work done. Potential energy is sometimes called stored kinetic energy.
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Gravitational PE When an object is lifted a distance h in the earth’s gravitational field, work is done against the force of gravity creating gravitational E P.
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Elastic PE The resisting force of a compressed or stretched spring is directly proportional to the displacement. (Hooke’s Law) spring constant
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Elastic PE When a spring is compressed or stretched a distance x, work is done against the elastic force of the spring creating elastic PE.
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Mechanical Energy The total kinetic energy and potential energy possessed by an object is called its mechanical energy (ME).
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Conservation Law In the absence of friction, the total mechanical energy remains the same. This is statement is called the Law of Conservation of Mechanical Energy.
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Rate of Work The rate at which work is performed is called power (P ).
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Rate of Energy Power can also be defined as the rate at which energy is created.
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