Question

Three equal weights $A,B,C$ of mass $2kg$ each are hanging on a string passing over a fixed frictionless pulley as shown in the figure. The tension in the string connecting weights $B$ and $C$ is

• A. zero
• B. 13 N
• C. 3.3 N
• D. 19.6 N

Answer 1

Answer: (B)

For $A:T-2g=2a\dots$ (i)
$\text{ For }B:T_1+2g-T=2a\dots (ii)$
For $C:2g-T_1=2a\dots (iii)$
Adding eqn. $(i)$ and $(ii),$ we get
$T_1=4a$
From eqns. $(iii)$ and $(iv)$ ,
$2g-4a=2a$
or $a=\frac{g}{3}$
From eqns. $(iv)$ and $(v)$,
$T_1=4\times \frac{9.8}{3}\approx 13N$