Assignment

1.) What is the difference between static, sliding, and viscous friction?

2.) An aluminum casting that weighs 10 lb is resting on a steel surface.

a. How much force will be necessary to get it started sliding?

b. How much force will be necessary to keep it sliding once it is moving?

2.) A robot arm must be able to extend 24 in. horizontally in 2 s while carrying a load of 10 lb. How much force is required, assuming the arm is accelerating all the way?

3.) A torque of 18 N · m is applied to a rotating part. The part has a moment of inertia of 0.078 kg · m2. How much time will it take to rotate the part 180°?

4.) An electric heater is rated at 220 Vac at 15 A. How many Btu/h of heat does it put out?

5.) A small gasoline engine can put out 18,000 N · m/min of mechanical power. The engine is used to drive an electric generator that is 80% efficient. Find the output of the generator in watts.

6.) What is diametral pitch, and why is it an important parameter in a gear mesh?

7.) For each gear pass shown in Figure 5.49, how many degrees must the big gear turn for the small gear to make two complete revolutions?

8.) Find the overall gear ratio of the gear train shown in Figure 5.50. If the motor is rotating at 500 rpm, what is the rotational velocity of the output gear?

9.) What are some advantages of transmitting power by belts?