The statement that forces are in equilibrium only when equal in magnitude, opposite in direction and collinear in action is an example of which concept?

The statement that forces are in equilibrium only when equal in magnitude, opposite in direction and collinear in action is an example of which concept?

• A. Principle of Transmissibility of a Force
• B. Axioms of Mechanics
• C. Characteristics of Force
• D. Scalar and Vector Quantities

Answer: (B)

The main idea is the condition for translational equilibrium: the total or resultant force on a body must be zero. For two forces to cancel each other completely, they must have the same magnitude, act in opposite directions, and share the same line of action. When these three requirements are met, there is no net force and no net moment about any point, so the body remains both non-accelerating and non-rotating. This reflects a fundamental assumption in mechanics—the axioms that underlie Newton’s laws and how forces interact with rigid bodies. The other options don’t capture this equilibrium criterion as directly. The principle of transmissibility is about moving a force along its line of action without changing its effect, which is related to the representation of forces but not the condition for equilibrium itself. The characteristics of force describe what a force is, not the balance condition. Scalar and vector quantities deal with how we describe quantities, not with the specific rule for when a system is in equilibrium.

The main idea is the condition for translational equilibrium: the total or resultant force on a body must be zero. For two forces to cancel each other completely, they must have the same magnitude, act in opposite directions, and share the same line of action. When these three requirements are met, there is no net force and no net moment about any point, so the body remains both non-accelerating and non-rotating.

This reflects a fundamental assumption in mechanics—the axioms that underlie Newton’s laws and how forces interact with rigid bodies. The other options don’t capture this equilibrium criterion as directly. The principle of transmissibility is about moving a force along its line of action without changing its effect, which is related to the representation of forces but not the condition for equilibrium itself. The characteristics of force describe what a force is, not the balance condition. Scalar and vector quantities deal with how we describe quantities, not with the specific rule for when a system is in equilibrium.