Laws of MotionMedium
Question
Given mA= 30kg, mB = 10kg, mC = 20 kg . The coefficient of friction between A and B μ1 = 0.3, between B and C μ2 = 0.2 and C , ground, μ3 = 0.1. The least horizontal force F to start motion of any part of the system of three blocks resting upon one another as shown in figure is (g = 10 m/s2)


Options
A.60 N
B.90 N
C.80 N
D.150 N
Solution
Maximum value of f1 = 0.3 × 30 × 10 = 90 N
Maximum value of f2 = 0.2 × 40 × 10 = 80 N
Maximum value of f1 = 0.1 × 60 × 10 = 60 N
⇒ Least horizontal force F to start motion = 60N

Maximum value of f2 = 0.2 × 40 × 10 = 80 N
Maximum value of f1 = 0.1 × 60 × 10 = 60 N
⇒ Least horizontal force F to start motion = 60N

Create a free account to view solution
View Solution FreeMore Laws of Motion Questions
A trolley is being pulled up an incline plane by man sitting on (as show in figure). He applies a force of 250 N. If the...Two block A and B of equal mass m are connected through a mass less string and arranged as show in figure. Friction is a...One end of a massless rope, which passes over a massless and frictionless pulley P is tied to a hook C while the other e...A 40 kg slab rests on a frictionless floor. A 10kg block rests on of the slap.The static coefficient of friction between...Two weights w1 and w2 are connected by a light thread which passes over a light smooth pulley. If the pulley is raised u...