Learning Path
Question & Answer1
Understand Question2
Review Options3
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Explore TopicChoose the Best Answer
A
The rougher the surface, the less normal force is needed.
B
The rougher the surface, the more normal force is needed.
C
Surface roughness has no impact on the normal force.
D
Normal force is inversely proportional to surface roughness.
Understanding the Answer
Let's break down why this is correct
Answer
When a smooth metal block sits on a rough surface, the roughness does not change the normal force; it is still equal to the block’s weight. What roughness does change is the static friction coefficient, μs, which is larger for a rougher surface. Because the maximum static friction is μs N, a higher μs allows the block to resist a larger horizontal push before sliding. Thus, on a rougher surface the block can stay in static equilibrium with a smaller applied horizontal force, even though the normal force remains the same. For example, a 10‑kg block on a rough floor (μs ≈ 0.
Detailed Explanation
Rougher surfaces have more bumps that press together. Other options are incorrect because Some think rougher surfaces mean the block is easier to hold, so less downward push is needed; Many assume roughness has no effect because only weight matters.
Key Concepts
Surface Roughness
Normal Force
Topic
Friction Coefficient Calculations
Difficulty
medium level question
Cognitive Level
understand
Practice Similar Questions
Test your understanding with related questions
1
Question 1When a block of metal is initially at rest on a heated surface, what effect does increasing the temperature have on the static friction coefficient compared to the kinetic friction coefficient once the block starts sliding?
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2
Question 2When a block of wood is resting on a concrete surface, which factor primarily influences the maximum static friction that can be exerted before the block starts to slide?
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3
Question 3A block of metal is placed on an inclined plane with a surface roughness that is significantly higher than that of the plane's opposing surface. If the angle of incline is 30 degrees, what effect does this combination of surface roughness and angle have on the maximum static friction experienced by the block?
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4
Question 4When a 15 kg block is placed on a rough surface where the coefficient of kinetic friction is 0.4, how does a significant increase in surface temperature affect the normal force and the friction acting on the block?
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