Block and Tackle Pulleys?

Question

Hey guys, i have a homework assignment and I was stuck on one problem, now im in middle school, so its nothing too complicated, i need the IMA of a block and tackle pulley, now I know there are many different kinds, but can someone tell me what the most common it? In the same problem, it asks for the IMA of a Single fixed pulley and a single movable pulley, for the movable the awnser is 2 and for the fixed its 1, so im gussing for the block and tackle it's 3, am i correct?

thanks

Answer 1

The theoretical mechanical advantage of a block and tackle is equal to the number of ropes supporting the load.

(2) pulleys (1 attached to ceiling and 1 to the load) would be (2) ropes for a mechanical advantage of (2).

(4) pulleys (2 attached to the ceiling and 2 attached to the load) would require (4) ropes for a mechanical advantage of (4).

See website: http://www.walterfendt.de/ph14e/pulleysystem.htm