Q. In the figure shown, a block of weight $10\ N$ is resting on a horizontal surface. The coefficient of static friction between the block and the surface $\mu_{s} = 0.4$. A force of $3.5\ N$ will keep the block in uniform motion, once it has been set in motion. A horizontal force of $3N$ is applied to the block then the block will
A) Move over the surface with constant velocity
B) Move having accelerated motion over the surface
C) Not move
D) First it will move with a constant velocity for some time and then will have accelerated motion
Explanation
(c) $F_{l} = \mu_{s}R = 0.4 \times mg = 0.4 \times 10 = 4N\ i.e.$ minimum $4N$ force is required to start the motion of a body. But applied force is only $3N$. So the block will not move
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.