Physics Applied

I was jamming through my Physics test today when I suddenly hit upon the extra credit question:
Extra Credit (3): For each chapter name how a concept from that chapter applies to either biology or medicine.

GASP!! Oh no! Physics are mathematical concepts! They don't apply to real life! So my head started throbbing like a car with its bass line volume turned to obliterate as I tried to think of something as fast as I could.

I think Dr. Marlowe was very worried for me since I was clutching my head and glaring at my paper. We made eye contact and he gave me a reassuring smile.
Anyways, I quickly made something up about how trees blowing in the wind and hormones working best at certain temperatures and blood running through veins and stuff. I don't think he's going to give me that extra credit.

Anyway, I was weeping tears of blood on the way home and explaining my woes to Alexie when she interrupted, "Why didn't you just think of a way you could kill someone using each of the principles you needed to apply? That would have been easy to remember."

That Alexie is one smart cookie, I'm telling you. Just out of curiosity I've been trying to follow her advice but simple harmonic motion (swaying trees) has got me stumped. Perhaps you could shoot waves at someone's brain causing it to vibrate and when it reaches resonance, it pops! or something...