Multiple choice

Why can friction never be entirely eliminated?

  1. No surface is perfectly rough.

  2. No surface is perfectly smooth.

  3. Surfaces can never be polished.

  4. Because dust particles present in air always make surface rough.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Friction exists because no surface is perfectly smooth - even polished surfaces have microscopic irregularities that create resistance when surfaces slide past each other. If surfaces were perfectly smooth, friction would be eliminated.

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