If you are bicycling fast enough you can cross a wooden plank spanning ditch before the plank breaks.
Normally we say this is because it takes time for the plank to deform and break when subjected to a weight. However, consider for a moment an alternative and naive(?) explanation: it because you weigh less when you are moving than when you are stationary. The idea is your motion reduces your gravitational mass ( independently of your inertial mass) while gravitational acceleration remains unchanged. While this theory is probably wrong, it would be easy to test in practice. See my 40k pdf file for an illustration of the theory. http://web.ncf.ca/eo200/dynamics/testing_weight.pdf Another test would be to take a bathroom scale on a plane or a train and weigh oneself. Has anyone done this by chance? Harry
