Here is a system of four police in such a configuration as shown, the idea is to provide a introduction to the concept of mechanical advantage also called leverage. Mechanical advantage is the ratio of the load lifted to the effort applied. As you can see the load lifted is much more than the effort applied does giving you some meaningful mechanical advantage meaning the number greater than 1. Here what is shown is or what is observed rather is a mass or the load corresponding to the mass of 1000 grams or 1 kilograms and here the effort is corresponding to the mass of 192 grams. So let us have a close up of each pulley and you can see each pulley is of the same type and same kind of bracket is used. So here the pulley has the mass of 23.7 grams and the bracket has the mass of 53 grams. So while in engineering textbooks typically the mass of the pull is ignored for purpose of computing mechanical advantage or leverage but in this real life situation here for this setup the mass of the pulley does matter. In particular the mass of the pulley and the bracket together makes a significant difference in computation of leverage when the load lifted and the effort applied are really small. However when the load lifted is much greater or load to be lifted is much greater than the mass of the pulley and the bracket or the contribution of weight due to the mass of the pulley and bracket become insignificant. So students are encouraged to look for such cases or instances wherein the mass of the pulley and bracket may be significant compared to the load lifted. So please do not make blind assumptions, assumptions without thought about the mass of the pulley and other accessories when you compute your mechanical advantage or in general creating a free body diagram or computing some variable corresponding to static equilibrium configuration. Again this is of course a static equilibrium configuration. Hope this was this video clip was meaningful and was worthy of your time spent on my channel with that said I will say goodbye and keep in touch or be sure to visit my channel for such educational video clips in future and if you are interested you can subscribe to my channel in which case you will be automatically notified by YouTube of new postings or new uploads. Thanks bye now.