Originally Posted by
Pedaleur
I get 3:1. The equivalent system has a load on pulley A and a cable fixed to its axle. This cable goes around pulley B (the tree) and back through pulley A, giving three tensions of cable acting on pulley A.
Much less in reality, of course.
No?
No. look up "block and tackle" in wikipedia - they seem to have it right.
Regardless, it's a good knot to know.