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? Force of friction = mu X weight

2.A small gasoline engine can put out 24,000 N-m/min of mechanical power.

The engine is used to drive an electrical generator that is 70 percent efficient.

1 N-m = 2.78 X 10-4 W-h.

Find the output of the generator in Watts.

Formula:

(N-m/min)( 2.78 X 10-4 w-hr/N-m)(60min/hr) = watts

output = efficiency X watts

3.A proportional controller for a rotating antenna has a gain of Kp of 5 in-oz/deg.

The antenna was initially pointing south, but was then commanded to point southeast.

Find the torque applied to the antenna in in-oz, when the antenna is within 5° of southeast.

torque = Kp X E

**Subject Engineering Electrical Engineering**