Q. A body of mass 10 kg is moving on a horizontal surface by applying a force of 10 N in forward direction. If body moves with constant velocity, the work done by force of fiction for a displacement of 2m is
A) $- 20\ J$
B) 10 J
C) 20 J
D) $- 5\ J$
Explanation
(a) Since body moves with constant velocity, so. Net force on the body is zero.
Here, $N = mg,F = f$
$\therefore W = \overrightarrow{\mathbf{F}}.\overrightarrow{\mathbf{s}} = fs\cos{180''}$
$= fs = - 10 \times 2 = - 20\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.