Question # 8:

Alternate Solution #2

All the rope, provided that the knife is such that: it can support
your weight when half the blade is stuck in ceiling, and it can bend
at the blade-handle junction without breaking.
Climb to top of the first rope, bringing other rope along. At the top,
stretch the second rope toward you and circle it around your waist.
Cut the first rope at the ceilling, hang on, and swing down on the
second rope. Climb back up to the ceiling. Pull up the other end ofthe
second rope, and tie it to the end of the first rope. Loop the tied
ropes around the handle of the knife. In one (quick) motion, cut the
second rope at the ceiling while pushing the knife into the ceiling.
Bend the handle of the knife enough so that the rope won't slip out.
Go down, hanging on the double rope with both hands. At the floor,
jerk hard to release the knife and the rest of the rope.

Alternate Solution #3

Climb up the first rope, carrying up the end of the second with you.
Cut the first rope, flush with the ceiling, swinging down on the second.
Climb up the second and cut that flush with the ceiling too, but only
part way, until it can just barely hold the rest of your weight.
Slowly climb down until you're just short of the bottom.
Tie a small loop here and climb up about two feet. Secure the loop
about your feet and fall to the ground (roughly three feet).
Just before your feet hit the ground the force of the fall will snap
the rope at the top.