thedoc wrote:GreatandWiseTrixie wrote:
The hammer analogy wouldn't work because air resistance would cause it to tumble.
No, if a hammer tumbles when thrown it's because of the dynamics imparted to it in the throw. Air resistance might cause the head of the hammer, being denser, to rotate to the front, but it would not cause the hammer to tumble during flight. It would be something like an arrow that has a denser, heavier tip and fletching at the back.
A hammer falling, if also in a rotation, will spin about it's own centre of gravity (the balance point through the length of head and shaft), air resistance will have little effect, and neither will gravity which will only effect the RATE at which it is attracted to the ground.
An arrow is designed to resist, in a straight line in the air, being light and having fletching. The area of the fletching is enough as, compared to the mass of the whole arrow, it is large.
Because a hammer is dense the air resistance due to the shape is minimal. But even an arrow dropped from a couple of feet on earth will not experience significant air resistance, in a simple fall.
In the case of a hammer being dropped on the moon, the hammer could be released in a way to achieve many rotations, far more than it could on earth, as the fall would take so much longer to reach the ground. OR, it just the same way it could be dropped so that no rotation happens.
If the hammer were released head up, head down or horizontally it would hit the ground in the same way. Rotation will only occur, if and when, a force is imparted on release. This will most commonly be the case.