Block A of mass 8 kg rests on a rough plane that makes an angle of with the horizontal
PHYSICS · Subjective · ISC · Physics · Laws of Motion · Laws of Motion
Problem
Block A of mass 8 kg rests on a rough plane that makes an angle of 25∘ with the horizontal. It is connected by a light, inextensible string that passes over a smooth pulley at the top of the plane to a hanging block B of mass mkg. The coefficient of static friction between block A and the plane is 0.35, while the coefficient of kinetic friction is 0.30. Take g=9.8ms−2.
(i) Derive an expression for the least value of m that will just start block A moving up the plane.
(ii) Using the value of m obtained in part (i), calculate the acceleration of the system once block A has started moving.
(iii) Find the tension in the string during this motion.
(iv) If block B is replaced by a mass 6 % greater than the value found in part (i), determine the new acceleration and comment on the effect of increasing the hanging mass.