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If the two rough surfaces are polished and put in contact, the friction force between them will __________.

  1. increase
  2. decrease
  3. remain constant
  4. Either increase or decrease

Answer (Detailed Solution Below)

Option 2 : decrease
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Detailed Solution

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CONCEPT:

  • Friction is the resistance force that opposes relative motion between two objects. 
    • It is not a fundamental force, like gravity or electromagnetism.
    • The direction of friction is always in such a way that it opposes the relative motion
  • The friction force between two surfaces is due to the roughness of the contact surface.

EXPLANATION:

  • The friction force between two surfaces is due to the roughness of the contact surface.
  • When the surfaces are polished, their roughness decreases.
  • They become smooth.
  • Hence the friction between them decreases.
  • So the correct answer is option 2.
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