DrPizza's Math and/or Science Challenge

[DrPizza]

Originally posted by: Demon-Xanth
#5:
He can steal all but about two feet needed to tie the knots.

Step 1: climb up rope #1 as far as possible
Step 2: cut rope #2 as high as possible
Step 3: cut rope #1 as high as possible that lets you tie a bowline
Step 4: tie a bowline in rope #1
Step 5: tie the cut ropes together with a square knot
Step 6: feed the rope through the loop in the bowline
Step 7: climb down the tied ropes
Step 8: pull the ropes through the loop, leaving only the small bowline at the top
Step 9: RUN!

Win!

 

[DrPizza]

Originally posted by: silverpig
Seems they've all been solved.

And the bike goes backwards.

Yes, of course. The problem was originally stated in a math journal in 1971. (Oddly, I remember it was math, I remember it was a 1971 issue, but I forgot which journal.)

 

[DrPizza]

Darkxshade's solution to #4 is fine. Here it is simpler to realize:

#4 *IS* tic-tac-toe:

2|7|6
------
9|5|1
------
4|3|8
(plus any reflections/rotations of this board)