Difficulty: Easy
Correct Answer: centre of gravity
Explanation:
Introduction / Context:Designers and analysts must know where the weight of a body can be assumed to act to simplify calculations of support reactions, stability, and tipping. This conceptual question distinguishes multiple “centres” used in mechanics.
Given Data / Assumptions:
Concept / Approach:The centre of gravity (CG) is the point where the resultant weight of the body acts. For a uniform gravitational field, the centre of gravity coincides with the centre of mass, but the term CG emphasizes the action point of weight (a force).
Step-by-Step Solution:
Identify the definition that refers to the line of action of weight.CG is defined as the unique point at which the entire weight can be assumed to act for any orientation.Therefore, among the given choices, 'centre of gravity' matches the definition.Verification / Alternative check:In a non-uniform gravitational field, CG and centre of mass may differ slightly. In standard terrestrial problems, they effectively coincide, validating the selection.
Why Other Options Are Wrong:
Common Pitfalls:Using centre of mass and centre of gravity interchangeably without noting the emphasis on force (weight) in the definition.
Final Answer:centre of gravity
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