What angle does an inclined surface make with the horizontal when an object on it is on the verge of sliding down__________________?
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Answer: C. repose
Explanation
The angle of repose is the maximum inclination angle of a plane with the horizontal at which an object on it remains at rest without sliding. At this specific threshold angle, the gravitational component pulling the object down equals the maximum static frictional force. Exceeding this critical angle causes static friction to be overcome, initiating downward sliding motion on the inclined surface. The tangent of the angle of repose is mathematically equal to the coefficient of static friction between the contacting surfaces. This angle depends on surface roughness, normal force, and material properties but remains independent of the object mass. Granular materials also exhibit an angle of repose, representing the steepest slope at which piled loose material remains stable.
Friction is a general physical phenomenon rather than the specific descriptive term for this critical boundary inclination angle. Limiting friction refers to the maximum resistive force value rather than the geometric angle of the inclined plane. Kinematic friction applies after relative sliding motion has already begun, whereas the angle of repose governs the verge of motion.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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