Part 1:

Question 1. An aluminum casting sits on a steel surface. Eight pounds of force is necessary to get it to start sliding. The static coefficient of friction (mu) for aluminum on steel is 0.61. What is the weight of the aluminum casting?

Question 2. A motor was measured to rotate (unloaded) at 5000 rpm, with a 6-V input and 1000 rpm, with a 1.2-V input. What is the transfer function (steady state) for the unloaded motor in rpm/V?

Question 3. In a certain system, an electrical heating element was found to increase the temperature of a piece of metal 10o for each amp of current. The metal expands 0.001 in./deg, and pushes on a load sensor that outputs 1 V/0.005 in. of compression. What is the overall transfer function inV/amp.

Question 4. Which of the following is a open-loop system?

Question 5. Find the gain in decibels of an amplifier that has a straight gain of 7000?

Question 6. Find the current in a ground loop that is 200 m long, has a wire resistance of 0.06 ohms/m, and has a difference of 4 V between grounds?

Part 2:

Question 1. Why would you use an optical isolator if you are connecting a microprocessor to a motor?

Question 2. Describe two ways to get the time when using position sensors to extract velocity information?

Question 3. How does a bimetallic temperature sensor work?

Question 4. Give an example of (1) a time-driven control system, (2) an event-driven control system, and (3) a combined time-and event-driven control system?