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This lecture explores the three main purposes of biomechanics: advancing academic knowledge, evaluating real-life situations, and serving as the only method of assessing certain model types. It discusses various types of models, such as static 2D models, static 3D whole-body models, and dynamic single-body segment static models, and their goals in determining forces associated with different body parts.
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Psyc 552Ergonomics & Biomechanics Lecture 8
Why Biomechanics? • 1… • 2… • 3…
3 Purposes • Advance “academic” knowledge • They evaluate real situations… • May be only method of assessing
Model Types • Static 2D… • Static 3D – Whole body models • Dynamic models
Single – Body Segment Static Model • Goal: Determine forces associated with a single body part. • Rotational moments • Reactive forces • To solve the problem we must: • 1. determine the magnitude of the external force acting on the stationary mass.
Measurement • Gravity creates the weight of the mass • Weight is proportional to mass • Weight = Mg • Weight is measured in Newtons • M = mass in kg • g = gravity 9.9 m/s2
Measurement (cont) • The weight of a 15 kg object would be… • Forces are vector quantities and depict…
Static Equilibrium • If the load is not moving… • When upward lift = weight vector we have static equilibrium… • The hands must create an equal reactive force in the opposite direction.
Moments • The tendency to rotate • The product of a force and the perpendicular distance from its line of action to the point of rotation.
