TOKSION 49 



463. Find the H.P. that can be safely transmitted by a hollow, 

 wrought-iron shaft making 100 RP.M., if the outside diameter is 

 8 inches and the inside diameter 5 inches. 



464. Find the ratio of the strength of a hollow circular shaft to that 

 of a solid circular one of the same material and the same section area. 



465. A solid shaft has a diameter of 12 inches and a hollow shaft 

 of the same material has an external diameter of 20 inches. Find 

 the internal diameter of the hollow shaft for the same section area, 

 and the ratio of their strengths. 



466. A hollow and a solid shaft are of the same material and same 

 section area. If the outside diameter of the hollow shaft is twice its 

 inside diameter, find the ratio of the strengths of the shafts. 



467. A solid shaft of structural steel is to transmit 300 H.P. at 

 200 RP.M. If the maximum moment is 30 per cent greater than 

 the average, find the diameter of the shaft for a factor of safety of 6. 



468. A hollow, structural steel shaft, outside diameter 6 inches, 

 transmits 300 H.P. at 200 RP.M. Find the inside diameter for a 

 factor of safety of 6. 



469. Find the H.P. that can be transmitted by a hollow, structural 

 steel shaft, 15 inches external diameter and 11 inches internal diam- 

 eter, at a speed of 50 RP.M., with a factor of safety of 4. 



470. A steel wire 0.18 inch in diameter and 20 inches long, is 

 twisted through an angle of 18.5 by a moment of 20 inch-pounds. 

 Determine the shearing modulus of elasticity of the wire. 



471. Find the shearing modulus of elasticity of a cast-iron bar 

 10 inches long and 0.82 inch in diameter, if twisted through an 

 angle of 1.3 by a twisting moment of 50 pound-feet. 



472. A shaft 15 feet long and 4.5 inches in diameter is twisted 

 through an angle of 2 by a moment of 2000 pound-feet. Find the 

 moment which will twist a shaft of the same material, 20 feet long and 

 7 inches in diameter, through an angle of 2.5. 



473. A round, cast-iron shaft 15 feet in length is acted upon by a 

 weight of 2000 pounds applied at the circumference of a wheel on 

 the shaft, whose diameter is 2 feet. Determine the diameter of the 

 shaft so that the angle of torsion shall not exceed 2. 



474. A steel shaft 20 feet in length and 3 inches in diameter trans- 

 mits 50 H.P. at 200 Pt.P.M. Through what angle is the shaft twisted ? 



