If a block A is moving downward at 10 ft/s while block C is moving down at 20 ft/s, determine the relative velocity of block B with respect to C.
1) 32 ft/s
be the distance of the block A from the datum line and SC,
SB be the distances of the blocks C and B from the datum line.
The total length of the cord L can be written as L = SA + 2SB
+SC. Differentiating the equation with respect to time we have
that VA + 2VB + VC
= 0 and 10 + 2VB + 20 = 0
So, velocity of B relative to C is 35 ft/s (upwards).