Tachometers measure the rotational speed of a shaft or disk and display the results as revolutions per minute (RPM). Tachometers can measure remotely or require physical contact. Common applications include measuring the speed of centrifuges, pumps, rollers, shafts, gears, motors and moving surfaces.
Stroboscopes can be used to study or measure rotating, oscillating or vibrating objects and their cyclic speed. When the speed of the strobe matches the frequency (or a fraction of the frequency) of a rotating or vibrating object, the object appears to be stationary or moving slowly forwards or backwards.
