The pulleys in the diagram are all smooth and light. The acceleration of $A$ is $a$ upwards and the acceleration of $C$ is $f$ downwards. The acceleration of $B$ is
The pulleys in the diagram are all smooth and light. The acceleration of $A$ is $a$ upwards and the acceleration of $C$ is $f$ downwards. The acceleration of $B$ is
$\frac{1}{2}(f-a)$ up
$\frac{1}{2}(a+f)$ down
$\frac{1}{2}(a+f)$ up
$\frac{1}{2}(a-f)$ up
The pulleys in the diagram are all smooth and light. The acceleration of $A$ is $a$ upwards and the acceleration of $C$ is $f$ downwards. The acceleration of $B$ is
From constrained
$-a-a_B-a_B+f=0$
$a_B=\left(\frac{f}{2}-\frac{a}{2}\right)=\frac{1}{2}(f-a) \uparrow$