# When is resultant force same as frictional force

Classified in Physics

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Angular Kinetics

Center of Mass: point around which mass or weight is considered to be concentrated. Determining COG: balance method, suspension method, MRI reconstruction, Segmental Segmental limitation: based on caucausian male cadavers, completed in 1930s, based on segments being truncated cones Mechanical stability: ability to maintain vertical projection of CG within base of support. ways to increase MS: increase mass, increase friction btwn body and surface, increased size of base support, Angular inertia: property of an object to resist changes in its angular motion. factors influence: radius has larger influence than mass. Center of Mass: point where gravitational force is applied balance Radius of gyration: point where mass can conceptually be concentrated such that it does not alter moment of inertia. Closer mass is is distributed to axis of rotation easier it is to rotate. The resistance to angular inertia is reduced. Angular momentum: angular analog of linear momentum , quantifies angular motion of object H=mk^2w 1st law angular: angular momentum of isolated system will remain the same regardless of any movements or torques as long as no external torque is applied. 2nd: change in angular momentum of an object is proportional to the net external torque exerted on it, and this change is in the direction. 3rd: Torque generated by one body part to rotate that part results in a counter torque by another body part.

Mechanics of Biolo

Stress: force internal per unit area over which the force acts. Strain: mechanical stresses cause strain. Deformation of a material with external force g=(L2-L)/L Viscoelasticity: stiffness and strength depend upon speed of applied load higher loading rate= increased stiffness Lower load= decreased stiff high load, few reps low load, many reps Forces: unaxial: compression, tension, shear Combined: bending, torsion Anisotropy: stiffness & strength depend upon mode of loading. bending: three point bending, cantilever bending. Bonde remodeling: alters size, shape & structure based on the imposed mechanical demands. As age progressive decrease in bone density, lower collagen & mineral content, lower mass, size.