I didn't want to do Physics so I did this instead.
Crochet Jellyfish Pattern
I have no crochet pattern writing experience, so bear with me.
Start with an Amigurumi double ring ( http://www.crochetme.com/amigurumi-double-ring ) with 5 scs. Pull double ring closed.
Rnd 1: Increase 5x by working 2 sc into each st. (10)
Rnd 2: [2 sc in one, sc] x 5 (15)
Rnd 3: [2 sc in one, sc] x 5 (20)
Rnd 4: dc every stitch
Rnd 5: sc every stitch. Make your stitches somewhat tighter. if needed, sl st all around one more time.
Now you're done with the "body" of the jelyfish. Flip it inside out, and sl st around the loops in the second to last row. Basically, stick your hook in that space between the dc and the sc and sl st that.
Every couple sl sts (its up to you, really), ch 9, turn, sc 2, then sl st down, and continue sl st-ing the inside. The number you chain for the tentacles is up to you, really :P.
Continue until you reach your starting point. sl st once more for good measure and break yarn. Proceed to throw jellyfish at siblings/family members/friends while screaming "Jellyfish attack!"