Static equilibrium

Definition

Static equilibrium occurs when an object is at rest and the sum of all forces and torques acting on it is zero. This means both the linear and rotational motions are in balance.

5 Must Know Facts For Your Next Test

1. For an object to be in static equilibrium, the vector sum of all forces acting on it must be zero: $\sum \mathbf{F} = 0$.
2. The sum of all torques acting on the object about any axis must also be zero: $\sum \tau = 0$.
3. An object in static equilibrium does not accelerate; both its linear and angular accelerations are zero.
4. Static equilibrium problems often involve analyzing forces such as tension, normal force, friction, and weight.
5. Solving static equilibrium problems typically requires breaking down forces into components and using conditions for both translational and rotational equilibrium.

Review Questions

Related terms

Torque:

A measure of the force that can cause an object to rotate about an axis. It is calculated as the product of the force and the lever arm distance from the axis: $\tau = r \times F$.

Normal Force:

The perpendicular contact force exerted by a surface on another object. It acts opposite to gravitational force.

Center of Mass:

The point where the mass of an object is considered to be concentrated. In uniform gravity, it coincides with the center of gravity.