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### Work

• If an object is displaced while some constant force acts on it, the work done by the force is the dot product of the force and displacement vectors.
• The work done in stretching (or compressing) a spring by a distance x is kx2/2, where k is the force constant of the spring.
• Work-Kinetic energy theorem: The work done on an object by the net force is equal to the change in kinetic energy:

Work done by net force = Final kinetic energy – Initial kinetic energy

• The potential energy of a system is the work done in assembling the system. For an object of mass m at a height h, near the surface of the Earth, the potential energy of the Earth-object system is mgh.
• If a spring is stretched (or compressed) by a distance x, then the elastic potential energy stored in the spring is kx2/2.
• Power is the rate of doing work; Power = F.v

## Work

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