## Question:

If block A is moving downward at 6 ft/s while block C is moving down at 18 ft/s , determine the speed of block B.

## Step-by-step

$s_{A}$+2 $s_{B}$+$s_{C}$=l
$v_{A}$+2 $v_{B}$+$v_{C}$=0
6+2 $v_{B}$+18=0
$v_{B}$=-12 ft/s=12 ft/s $\uparrow$