O000188 – Physics 2: Vibration, Waves and Thermodynamics 1st year of Joint Section Bachelor of Science in Environmental Technology, Food Technology and Molecular Biotechnology Chapter 10 The conditions for equilibrium ๏ท For an object to be at rest, Newton’s second law states that the sum of the forces must add up to __. This is the first condition of equilibrium. o Σ๐น๐ฅ = ___, Σ๐น๐ฆ = ___, Σ๐น๐ง = ___ ๏ท For an object to be at rest, the net torque applied must be added to __. o Σ๐ = ___ ๏ท In other words, the net force and net torque must equal __. Stability and balance ๏ท _____: The object returns to its original position. ๏ท _____: The object moves farther from its original position. ๏ท _____: The object remains in its new position. Elasticity; Stress and strain ๏ท Elasticity and Hooke’s Law o ๐น = __ ∗ __ ๏ท Youngs Modulus o โ๐ = _____ o The Elastic moduli is same/different for different materials. ๏ท Stress and Strain ๐น๐๐๐๐ o Stress = ๐ด๐๐๐ = __ o Strain = ๏ท ๐โ๐๐๐๐ ๐๐ ๐๐๐๐๐กโ ๐๐๐๐๐๐๐๐ ๐๐๐๐๐กโ = __ Relationship between Youngs Modulus, Stress, and Strain ๐๐ก๐๐๐ ๐ /๐๐ก๐๐๐๐ ๐น/๐ด o ๐ธ = ๐๐ก๐๐๐ ๐ /๐๐ก๐๐๐๐ = โ๐/๐ 0 Tension, Compression, and Shear Stress ๏ท When a rod is being stretched, it is under _____ stress. ๏ท When a rod is being “squashed”, it is under _____ stress. ๏ท When a book is being pushed parallel to the ground, it is under _____ stress. ๏ท Shear Modulus ๐ ๐น o ๐บ = โ๐0 ๐ด ๏ท Bulk Modulus โ๐ o ๐ต = − โ๐/๐ 0 Fracture ๏ท Safety factor o If the safety factor for Aluminum is from 5 to 10, the actual stress on the structure should not exceed _____ to _____. Arches and Domes ๏ท Arches and Domes are special ways to span a space that allow the ____ to be managed well.