ME 360 Midterm: ME 360 Alabama Test3 Fall07
Document Summary
Piezoresistive accelerometers work by converting the force applied to a known mass (a=f/m) into a resistance change measured by a wheatstone bridge. Accelerometers are frequently used to measure high frequency vibrations ( > 1000 hz). Pwm stands for partial weighting method - a way to vary the speed of an electric motor. The synchronous speed of an ac motor depends on input frequency and number of poles. Incremental encoders are usually less expensive than absolute encoders since they require fewer wires and optical sensors to operate. Lvt"s and lvdt"s are used to measure linear displacement. When used as a tachometer, a dc motor will produce a voltage that is proportional to the angular velocity. Timer based methods always give an average value for measured velocity. Short answer questions - use the space provided for written answers: [5] name three (3) different types of single phase, fractional horsepower ac motors.
