Question

Two blocks B₁and B₂of masses m₁and m₂respectively are connected with the help of a pulley and string as shown. Upper surface of vehicle is smooth but vertical surface is rough.

Given a = g/7 and m₁ = 7.5 m₂. Coefficient of friction between block B₂and side of vehicle is

• A. 0.4
• B. 0.5
• C. 0.6
• D. 0.3

Answer 1

Answer: (B)

0.5

Answer 2

For equilibrium

T = m₁a ………. (i)

and T = m₂ g + μm₂a …….. (ii)

From (i) and (ii)

m₁a = m₂g + μm₂a

or μ = $\frac { m _ { 1 } a - m _ { 2 } g } { m _ { 2 } a }$

= $\frac { m _ { 1 } \left( \frac { g } { 7 } \right) - m _ { 2 } g } { m _ { 2 } \left( \frac { g } { 7 } \right) } = \frac { m _ { 1 } - 7 m _ { 2 } } { m _ { 2 } }$ = $\frac { 7.5 m _ { 2 } - 7 m _ { 2 } } { m _ { 2 } } = 0.5$