Question

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 1

Correct Answer - Option 2 : decrease

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.