Hmm, have you read Aristotle? So far as I can tell, his most extended argument on the matter is Physics IV.8, where he argues that in an atmosphere, heavier things fall faster because they are better able to divide the medium owing to greater downward force. He then argues that in a void, heavier and lighter things would fall with the same speed. Since this is not what we observe (we do in fact often observe heavier things falling faster for the reason Aristotle cites) there cannot be any void.
Aristotle is complicated and surprising, and rarely does any common knowledge capture his views well.
Meh. I don’t think many people would expect an open umbrella to fall through air faster than a pen cap does, even though everybody knows the former is heavier.
I’m reminded of a mechanics exam in college that involved calculating the trajectory and location/velocity at impact of a parachutist jumping from an airplane. (”… Ignore air resistance.”)
I had a similar one, too. (After noticing people laughing, the professor did say something like “that only applies to the time before the parachute is opened”, IIRC.)
“The shape of bodies will not account for their moving upward or downward
in general, though it will account for their moving faster or slower.
The reasons for this are not difficult to see. For the problem thus
raised is why a flat piece of iron or lead floats upon water, while
smaller and less heavy things, so long as they are round or long-a
needle, for instance-sink down; and sometimes a thing floats because
it is small, as with gold dust and the various earthy and dusty materials
which throng the air....Thus the reason why broad things
keep their place is because they cover so wide a surface and the greater
quantity is less easily disrupted. Bodies of the opposite shape sink
down because they occupy so little of the surface, which is therefore
easily parted. And these considerations apply with far greater force
to air, since it is so much more easily divided than water. But since
there are two factors, the force responsible for the downward motion
of the heavy body and the disruption-resisting force of the continuous
surface, there must be some ratio between the two.”
-Aristotle, On the Heavens, IV.6
No one is arguing that Aristotle is right about science, mind you. He was obviously not. I’m just saying his views aren’t often well represented by common opinion. This isn’t terribly important, since Aristotle isn’t terribly important, but I thought it was worth pointing out.
Meh. I don’t think many people would expect an open umbrella to fall through air faster than a pen cap does, even though everybody knows the former is heavier.
I’m reminded of a mechanics exam in college that involved calculating the trajectory and location/velocity at impact of a parachutist jumping from an airplane. (”… Ignore air resistance.”)
I had a similar one, too. (After noticing people laughing, the professor did say something like “that only applies to the time before the parachute is opened”, IIRC.)
-Aristotle, On the Heavens, IV.6
No one is arguing that Aristotle is right about science, mind you. He was obviously not. I’m just saying his views aren’t often well represented by common opinion. This isn’t terribly important, since Aristotle isn’t terribly important, but I thought it was worth pointing out.