Skidding on a level circular path A vehicle moves on a level circular track. Skidding can be avoided if the available frictional force between the tyres and the road is __________ the required centrifugal (outward) force for the turn.
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Aless than
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Bgreater than or equal to
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Cequal to
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Dgreater than
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Emuch less than
Answer
Correct Answer: greater than or equal to
Explanation
Introduction / Context:Cornering safety depends on whether tyre–road friction can supply the lateral (centripetal) force needed for circular motion. If insufficient, the vehicle skids outward.
Given Data / Assumptions:
- Level road (no banking), so lateral force is provided solely by friction.
- Centripetal force required: m * v^2 / r directed toward the centre of the curve.
- Maximum available static friction: F_max = μ_s * N = μ_s * m * g.
Concept / Approach:For no skidding, the maximum available static friction must meet or exceed the required centripetal force. If the requirement exceeds what friction can provide, tyres will slide, producing skid.
Step-by-Step Solution:
Required: F_required = m * v^2 / r.Available: F_available = μ_s * m * g.Condition for no skidding: F_available ≥ F_required.Therefore, friction must be greater than or equal to the centrifugal tendency that must be countered.Verification / Alternative check:If μ_s * g = v^2 / r exactly, the tyres are at the limit of adhesion (impending skid). If μ_s * g is larger, there is a safety margin and no skidding occurs.
Why Other Options Are Wrong:
- Less than / much less than: Guarantees skidding because friction cannot supply the needed centripetal force.
- Equal to: Only the limiting case; while it avoids skidding, the general safe condition is 'greater than or equal to'.
- Greater than: True but excludes the limiting (equality) case where skidding just does not occur.
Common Pitfalls:Confusing 'centripetal' and 'centrifugal' descriptions. In vehicle dynamics we require sufficient inward (centripetal) frictional force; outward 'centrifugal' is an apparent effect in the rotating frame.
Final Answer:greater than or equal to