Multiple choice

Work done against friction is

  1. negative

  2. positive

  3. zero

  4. None of these

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Work done against friction is negative because the frictional force always acts opposite to the direction of displacement. When we calculate work as W = F·d·cos(theta), the angle between friction force and displacement is 180°, giving cos(180°) = -1. This negative work represents energy dissipated as heat.