Force and pressure {stress, physics}| tend to alter object structure. I-beam, twisting torsion bars, and standing up use material stresses, strains, and strengths.
Mechanical forces {compression}| can be pushes on materials.
Mechanical forces {tension, force}| can be pulls on materials.
Mechanical forces {torsion, force}| can be twists on materials. Torsion is simultaneous push in one direction and pull in another direction.
Stress S is proportional to length change dL divided by length L {Hooke's law} {Hooke law}: S = k * (dL / L). Pressure compresses material against restoring force. Restoring force F varies with material type k and distance compressed x: F = -k * x. Pressure is compression force F divided by area A: P = F/A. Pressure equals restoring force -k*x divided by area A: P = F/A = -k * x / A. Constant k depends on Young's or other elasticity modulus u, cross-sectional area A, and object length L: k = A * u / L.
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Date Modified: 2022.0225