Equilibrium of Rigid Bodies
This final section extends equilibrium concepts to rigid bodies, introducing the idea of torque and rotational equilibrium.
Definition: A rigid body is in equilibrium when both the net force and the net torque on the body are zero.
Conditions for equilibrium:
- ΣF = 0 translationalequilibrium
- Στ = 0 rotationalequilibrium
Vocabulary: Torque τ is the rotational effect of a force and is calculated as τ = r × F, where r is the position vector from the axis of rotation to the point of force application.
For a two-dimensional problem, the torque equation becomes:
Στ = Σr⊥F = 0, where r⊥ is the perpendicular distance from the axis to the line of action of the force.
Example: A ladder leaning against a wall with a person standing on it. Calculate the reaction forces at the ground and wall.
Steps to solve:
- Draw a free-body diagram showing all forces.
- Choose a convenient point for calculating torques usuallyapointthateliminatesunknownforces.
- Apply ΣFx = 0, ΣFy = 0, and Στ = 0.
- Solve the resulting system of equations.
Esercizi vettori Zanichelli pdf often include such complex equilibrium problems to challenge students' understanding of both force and torque concepts.
Highlight: The choice of the rotation point for torque calculations can significantly simplify the problem-solving process.
Operazioni con i vettori esercizi involving rigid body equilibrium provide excellent practice in applying vector concepts to real-world physics problems.