PHYS 1080 Lecture Notes - Lecture 9: Stress (Mechanics), Compressive Stress, Shear Stress
5 Dec 2016
School
Department
Course
Professor
Document Summary
Depending on the type of material, some things ,ay deform more readily than others. Apply large enough force, eventually it"ll break. Consider a cylinder of cross-sectional area a and length lo: = young"s modulus (units are n/m2 = pa (cid:447) = . Imagine jumping down a 3. 0 m wall. Leg bone ~0. 3 m long (lo), with a cross-sectional area 4. 0 x 10-4 m2 (a) Force of compression when landing: 1. 5 x 103 n (f) Y. c for bone is 9. 0 x 109 n/m^2 (y) 1. 5x103/ 4. 0x10-4 = 9. 0x109 ( l/0. 3) = 1. 3x10-4 m. Apply a force and the object will deform. Point a) proportional limit- end of linear regime. Point b) elastic limit or yield point- irreversible changes. Ductility- ability to deform (elongate) under tensile stress. Brittleness- materials that factor with very little strain. Consider a block of cross-sectional area a and thickness l: Fs/a = g(x/l) = g tan o ~ go.
