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Mechanics

Graphs Describing S.H.M.

Energy against time

If an oscillation is s.h.m., then the total energy possessed by the oscillating body does not change with time.

An oscillation in which the total energy decreases with time (usually because of air resistance or something similar) is described as a damped oscillation.

Total energy against time (constant)

Kinetic energy against time ½m(rwcoswt)²

Potential energy against time

Knowing the form of the K.E. graph and the fact that the total energy is constant, we can deduce that the P.E. graph has the same form as the K.E. graph but is inverted.

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© David Hoult 2008