name this type of device that measures the angular speed of a rotating shaft, which, for 10 points, is often used in automobiles in association with a speedometer.
The resonance, or vibrating-reed, variety uses a series of consecutively-tuned reeds to match the vibration frequency of the machine.  The mechanical type takes advantage of the fact that the centrifugal force on a rotating mass can be used to stretch or compress a spring.  The eddy-current, or drag, type uses a magnet rotating with the subject to produce eddy currents that are proportional to the magnet's speed, and a stroboscope can also be used to simulate this instrument. name this type of device that measures the angular speed of a rotating shaft, which, for 10 points, is often used in automobiles in association with a speedometer.
The resonance, or vibrating-reed, variety uses a series of consecutively-tuned reeds to match the vibration frequency of the machine.  
tachometer (tack-AH-meter)