222_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

222_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Sec_2.8-2.12.qxd 216 9/25/08 11:44 AM Page 216 CHAPTER 2 Axially Loaded Members Problem 2.8-7 A weight W 4500 lb falls from a height h onto a vertical wood pole having length L 15 ft, diameter d 12 in., and modulus of elasticity E 1.6 106 psi (see figure). If the allowable stress in the wood under an impact load is 2500 psi, what is the maximum permissible height h? W = 4,500 lb h d = 12 in. L = 15 ft Solution 2.8-7 Weight falling on a wood pole E 106 psi 1.6 2500 psi ( allow max) Find hmax STATIC STRESS sst W A 4500 lb 39.79 psi 113.10 in.2 MAXIMUM HEIGHT hmax 59): smax Eq. (2 sst c 1 + a 1 + 2hE 1/2 bd Lsst or smax 2hE 1/2 1 a1 + b sst Lsst Square both sides and solve for h: h W 4500 lb L 15 ft d 12 in. 180 in. A pd 4 2 113.10 in. Lsmax smax a 2E sst 2b ; SUBSTITUTE NUMERICAL VALUES: hmax 2 hmax (180 in.) (2500 psi) 2500 psi a 2(1.6 * 106 psi) 39.79 psi 8.55 in. ; 2b ...
View Full Document

Ask a homework question - tutors are online