Text: The time rate of change of velocity. For harmonic motion, this is often expressed as G, A, x, or d2x/dt2. Acceleration leads displacement by 180 degrees in time. Typical units for acceleration are feet per second per second (ft./sec.2), meters per second per second (m/sec.2), or more commonly G's (where G = acceleration of gravity = 32.17 ft./sec.2 = 9.81 m/sec.2). Acceleration measurements are generally made with piezoelectric accelerometers and are typically used to evaluate high frequency machine casing or bearing housing response characteristics.

See Also: ODD INTEGER; GRAVITY

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