do accel vs. ramp slope expt 'blind': time with pendulum, you give screw a carefully-counted number of turns, we repeat

maybe do similarly with audacity

expt: ball up, down incline
timing by range of pend lengths from clearly before to clearly after ...
`dPE, `dKE, `dW_frict, `dKE_rot ...

tees for collision experiments

two magnets connected by threads, burn central thread and observe reaction; or use cars on near-const-vel inclines

compare `dPE with `dKE of ball on incline; considering very low rolling friction, where is the rest of the energy?