Question

Two masses A and B of 10 kg and 5 kg respectively are connected with a string passing over a frictionless pulley fixed at the corner of a table as shown. The coefficient of static friction of A with table is 0.2. The minimum mass of C that may be placed on A to prevent it from moving is

• A. 15 kg
• B. 10 kg
• C. 5 kg
• D. 12 kg

Answer 1

Answer: (A)

15 kg

Answer 2

For limiting condition

$\mu = \frac { m _ { B } } { m _ { A } + m _ { C } }$ ⇒ $0.2 = \frac { 5 } { 10 + m _ { C } }$

⇒ $2 + 0.2 m _ { C } = 5$ ⇒ $m _ { C } = 15 \mathrm {~kg}$