Apologies for the light posting. Busy week, and it’s going to be a busy weekend too in physics land. Well, that’s what I signed up for.
This caught my eye though. Via Swans on Tea though, I see a great demonstration of physics as art. There’s a story of Feynman and several other physics lecturers who liked to attach a bowling ball to the high roof of their lecture halls and pull the ball out to an angle right by their faces and let it swing. Of course it comes almost back to hit them in the face,but not quite. The laws of nature just can’t provide more energy than went in to the system.
This is roughly the same principle, but with momentum. Conservation of momentum holds that the absence of external forces is equivalent to the statement that the velocity of the center of mass remains constant – stationary in many cases. Now there is an external force here – the forces of gravity and the normal force from the floor.
The center of mass isn’t over the edge of the support when the hammer starts, and so it won’t be when the hammer hits – assuming the structure doesn’t deform and assuming you understand how the structure interacts with the floor. This artist does, and so the structures stay upright… barely!