What defines static equilibrium in a body?

What defines static equilibrium in a body?

• A. The total weight of the body is equal to its mass
• B. The sum of forces and moments acting on the body are zero
• C. The body is in continuous motion
• D. The body has an unbalanced force acting upon it

Answer: (B)

Static equilibrium in a body is defined by the condition that the sum of all forces and the sum of all moments (or torques) acting on the body are zero. This means that there is no net force causing the body to accelerate in any direction, nor is there a net moment causing it to rotate. Essentially, for an object to be in static equilibrium, it must be at rest and not experiencing any changes in its motion, ensuring that all internal and external forces balance each other out perfectly. For example, consider a book resting on a table. The gravitational force pulling the book down is exactly countered by the normal force exerted by the table pushing up, resulting in no movement. Similarly, if there are no unbalanced moments, the book will not start to rotate. This balanced state is crucial in engineering and physics when analyzing structures and mechanisms to ensure stability and safety.

Static equilibrium in a body is defined by the condition that the sum of all forces and the sum of all moments (or torques) acting on the body are zero. This means that there is no net force causing the body to accelerate in any direction, nor is there a net moment causing it to rotate. Essentially, for an object to be in static equilibrium, it must be at rest and not experiencing any changes in its motion, ensuring that all internal and external forces balance each other out perfectly.

For example, consider a book resting on a table. The gravitational force pulling the book down is exactly countered by the normal force exerted by the table pushing up, resulting in no movement. Similarly, if there are no unbalanced moments, the book will not start to rotate. This balanced state is crucial in engineering and physics when analyzing structures and mechanisms to ensure stability and safety.