Question

Figure shows a system of four pulleys. The upper two pulleys are fixed and the lower two are movable. What is the velocity ratio of the system?

Answer 1

Given:
The block and tackle system consists of 4 pulleys, i.e. $n=4$
In a block and tackle system of $n=4$ pulleys, if the load moves up through a distance d, each segment of string supporting the load gets loosened by a length d.
So if $d_L=d$ then distance moved by the effort end is $d_E=nd=4d$
So the velocity ratio is
$V.R.=\frac{d_E}{d_L}=\frac{nd}{d}=n=4$