Question

Three blocks are arranged as shown in which ABCD is a horizontal plane. Strings are massless and both pulley stands vertical while the strings connecting blocks m₁ and m₂ are also vertical and are perpendicular to faces AB and BC which are mutually perpendicular to each other. If m₁ and m₂ are 3 kg and 4 kg respectively. Coefficient of friction between the block m₃ = 10 kg and surface is m = 0.6 then, frictional force on m₃ is –

• A. 30 N
• B. 40 N
• C. 50 N
• D. 60

Answer 1

Answer: (C)

50 N

Answer 2

Net force on m₃ = $\sqrt { ( 30 ) ^ { 2 } + ( 40 ) ^ { 2 } }$ = 50 N

and limiting friction on m₃ = mm₃g = 60N

\ System remain in equilibrium and friction on m₃ = 50 N