I'm sorry,rl.bhat.I still don't get it.
final length= b+d
initial lenght = b
so substracting gives me -b
and for C,
final length = d-c
initial length = c
and subtacting to find the net change in segment gives me = d-2c ?
In the problem it is said that B moves 2.44 m in 2 seconds.
In 2.44 m(b) includes fall of the mass B, which changes the length of the rope segment, plus fall of the pulley D(d), which does not change the length of the rope segment
To calculate the net change in the length of the rope, we must know the change in the rope segment of the mass B alone.And that is b - d