Tuesday, March 3, 2009

If I Wrote a Textbook...

Figure 1: Godzilla looms over Billy.
Godzilla's foot is towering 0.3m above Billy's head. If Godzilla's foot weighs 200 kg and Godzilla's leg muscles exert a force FA of 30 Newtons onto the foot acting downwards at an angle of 30 degrees to the horizontal ground plane (see diagram), how much time does Billy have to move to avoid being flattened?

See now this is the type of problem people can relate to.

[Bonus: Write a differential equation expressing a werewolf's rate of change with respect to the phase of the moon. Use this equation to calculate how quickly someone needs to be locked in a cage once they start transforming, given that signs of werewolf behavior are detectable after the transformation is 20 percent complete. Use a safety factor of 1.2 and assume the lock is sturdy.]

EDIT: A few corrections for the first problem: assume that Godzilla's foot is large enough that it's horizontal motion in the brief time before impact can be neglected and that the foot will indeed impact Billy if he does not move. Furthermore, assume the foot has no velocity at the instant depicted in the question. Resolution of ambiguities in the bonus question are left as an exercise to the student, but be sure to state all assumptions and reasoning.

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