A wooden block of mass rests on a horizontal rough table
PHYSICS · Subjective · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A wooden block of mass 5.0kg rests on a horizontal rough table. A force F is applied to the block by pulling with a light string that makes an angle 30∘ above the horizontal. The least value of F required to just start moving the block is found to be 22N.
(a) Draw the free–body diagram of the block showing all forces when the pull is at the limiting value.
(b) Write the conditions of limiting equilibrium for the block and obtain simultaneous equations involving F, the normal reaction R, and the coefficient of static friction μs.
(c) Using the given numerical data, calculate μs between the block and the table.
(d) Keeping the same angle of pull, what pull would keep the block moving with constant velocity once motion has started, if the coefficient of kinetic friction is 75% of the value obtained in (c)?