Friction — Type at Rest The friction experienced by a body when it is at rest (before impending motion) is called:

Introduction / Context: Frictional behavior differs for bodies at rest versus in motion. Correct terminology matters when calculating forces needed to initiate versus maintain motion in machine elements and contact problems.

Given Data / Assumptions:

• Body is at rest relative to the surface.
• External force may be applied but remains below the threshold that causes slipping.

Concept / Approach: Static friction adjusts up to a maximum value to oppose impending motion: F_s ≤ μ_s N. The maximum value at the verge of sliding is called limiting friction (F_lim = μ_s N). Once motion starts, the resisting force becomes kinetic/dynamic friction F_k = μ_k N with μ_k < μ_s typically.

Step-by-Step Solution:

Verification / Alternative check: Simple block-on-plane experiment: gradually increase pull; friction increases correspondingly until a maximum is reached (limiting), after which motion begins and friction drops to kinetic.

Why Other Options Are Wrong: “Dynamic friction” refers to motion; “Limiting friction” is a specific maximum value, not the general name; “Coefficient of friction” is a dimensionless property μ, not a force.

Common Pitfalls: Using μ_s N (limiting) for all static cases; forgetting that static friction can be less than its maximum depending on applied load.

Final Answer: Static friction.