B-1

Calculate the torsional stress in the shaft of a blower from the following data: shaft diameter 2 in., speed 200 rpm, total head of air equivalent to 2 in. WG, volume discharged 30,000 cfm, and blower efficiency 60 per cent.

B-2

A truck body lowers 5 in. when a load of 25,000 lb is placed on it. What is the frequency of vibration of the truck if the total spring-borne weight is 40,000 lb?

B-3

A mass weighing 25 lb falls a distance of 5 ft upon the top of a helical spring having a spring constant k of 20 lb per in. ( a) What will be the velocity of the mass after it has compressed the spring 8 in.? ( b) Calculate the maximum compression of the spring.

B-4

Investigate the acceptability of the fan and motor drive shown from the standpoint of possible excessive vibration. Motor: a-c 110 volts, 60 cycls, 2,400 rpm. Armature: 40 lb. Radius of gyration: 5 in. Three-blanded fan: wt 10 lb; radius of gyration 9 in. Shaft is of steel. If design is not acceptable, indicate what changes should be made.

Figure B-1

B-5

A 22-coil squared and ground spring is designed to fire a 10-lb projectile into the air. The spring has a 6-in. diameter coil with 3/4-in. diameter wire; it has a free length of 26 in. and is compressed 8 in. when loaded or set. The shear elastic limit for the spring...