Here's the weeding out question from my intro physics final. We had been studying pendulums (pendula?), levers and rotation. Then on the final:

Consider a hockey stick laying on the ice. (To simplify, one-dimensional rod on a frictionless surface.) It is struck by a hockey puck, traveling perpendicular to the stick, transferring 100% of its energy. In terms of length of the stickl, distance from the end of the stick of the impactd, mass of the stickm, mass of the puckm', and velocity of the puckv, describe the resulting motion of the stick as it travels and/or spins on the ice.

Sure, I'd like to have spent some time working with the formulas for two- and three-dimensional problems like that. But this was asking us to

*derive*those formulas on-the-fly during a timed exam.