There's no such thing as acceleration of just the ball. Everything is relative; there are no fixed bodies. We just ignore the movement of the earth in these things, because as far as approximations go, it makes no practical difference.

They would not cross an imaginary line at the same time, since if the earth is modelled as a perfect sphere, it will be pulled slightly toward the bowling ball (the actual vector being somewhere between them because the feather has a small moment). If there's a 1 degree difference in the drop between the feather and ball, which looks about right for this experiment, this will result in a 1.7% advantage for the bowling ball hitting the earth first from the very slight movement of the earth.

Even with a small degree difference, you can do the trig to show the bowling ball would hit first.

I don't mind approximations. At all. It just should be presented in the full form, with the note you can drop the mass of one object from the equation when it is dominated by the other mass. This way people won't learn bad physics.

Technically correct is the best kind of correct.

The trouble with teaching people that the bowling ball and feather will hit at, quoting the physicist in this clip, "exactly the same time", is that (relativity issues aside making the statement a joke anyway) it leads people to have a faulty understanding of how gravity actually works.

It's fine to teach that bowling balls and feathers will hit at *approximately* the same time, due to one mass in the equation being much higher than the other (allowing us to approximate it out), but it seems to never be taught this way. So these students end up with all sorts of wrong ideas about gravity when they get to me to work on n-body solvers.

It's the same problem, for example, as teaching elementary school kids that 5 divided by 0 is 0. It might make that teacher's life a little easier, but causes problems downstream.

Now I'm starting to think you just want to argue. If you're smart enough to make those technical assertions, you're smart enough to know that's not what the experiment was about, and that you're just adding data to confuse the lesson.
The experiment is about the effect of gravity on the moving objects under 2 conditions, and how their mass means nothing when determining THEIR accelerations/speeds in a vacuum. Period.
You want to introduce other, completely unobservable (and irrelevant to the lesson) forces and movements to say 'nope'. Technically, you may be correct in a way, but you must completely ignore the purpose and parameters of the experiment and assume inobservably small movements to make your point...a point that does not actually change the experimental findings or the lesson, but does confuse it thoroughly.

EDIT: I would note that, by your standards, exactly where the observer is positioned makes MORE difference than the different masses of the bowling ball and feather, as do the exact positions of the two...if dropped from exactly the same position, they hit at exactly the same time because their gravitational forces are in line.

I would also note that if you change it to say, unimpeded, they would cross any imaginary line in space at the same time (essentially what they mean), again your point becomes moot.

If a planet would hit before a feather, then a bowling ball would hit before a feather. The only difference is the effect size.

Ugh, so wrong. The gravitational force between two objects is proportional to the product of both masses. So a more massive object will indeed fall faster than a lighter object.

We can't really see it with a bowling ball and a feather, but we really shouldn't be teaching that all objects fall at the same speed.

My guess would be Inertia. Even in a vacuum objects have Inertia.

"Inertial mass is the mass of an object measured by its resistance to acceleration"

Deformable objects might deform slightly as they accelerate (feather).
However, their center of gravity is the same as a rigid object (bowling ball)

Seems like no one else noticed or cared, but why is it that in the zero-air environment when they did the release the tiny "strands of feather" (I don't know what each little thread on a feather is called, if anything) looked like they were getting pushed back by air?

Am I seeing things?

It must be a hoax. They're probably on a sound stage where they faked the whole thing. Probably not even a real bowling ball.

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WOW, that vacuum slowed down the bowling ball to the speed of a feather. Pretty cool. That's why nothing can go faster than the speed of light.

Its definitely relativity.

They fall at the same speed? As each other? With respect to what? Why are they even falling at all?

In relativity you always have a frame of reference. If you take the speed of feathers with respect to that of the bowling ball in a vacuum, the difference is zero....they aren't moving at all within the frame of reference.

No need to complicate things by bringing the earth into the equation.

Its a round about way of using something so simple to explain how relativistic equations are handled in his works.

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Yeah, those last couple sentences throw me for a loop also. I *think* he is referencing relativity, in that the objects are behaving relativistically towards each other, but if you remove/ignore the earth (and air) then you are missing one half of what they are "relative" to. Or that the Earth and the air are also (minutely) attracted towards the bowling ball and feather, or something.

Would definitely be nice to see the next few minutes of this show to see what he's eluding to...

I would also guess that when a baseball hits a bowling pin, it most likely doesn't emit the exact same sound as when a bowling ball hits it.

And the best part? That's a 16 pound bowling ball.