Block and tackle system

[shelli8]

Hi, I had some luck on this forum before, and here I am stumped again. Hey, I am just learning this stuff. I am not even necessarily looking for an answer, I cant find a formula for this one. It says "A block and tackle system has three pulleys in each of two blocks. If a downward effort of 100 N is applied and the machine has an efficiency of 83.6%, what is the maximum mass that can be moved?" The answers are in kgs. Any thoughts or ANYTHING appreciated!

[shelli8]

thanks anyways!

[russ_watters]

In any case, there are basically 2 things to remember:

1. Count the number of strands of rope. Thats the factor you multiply force by and divide distance by (aka "mechanical advantage")
2. Be careful of pulleys that serve only to re-direct force, but don't add to the mechanical advantage.

Welcome to the board.