Posted on 11/02/2011 3:14:29 PM PDT by SunkenCiv
Explanation: If you drop a hammer and a feather together, which reaches the ground first? On the Earth, it's the hammer, but is the reason only because of air resistance? Scientists even before Galileo have pondered and tested this simple experiment and felt that without air resistance, all objects would fall the same way. Galileo tested this principle himself and noted that two heavy balls of different masses reached the ground simultaneously, although many historians are skeptical that he did this experiment from Italy's Leaning Tower of Pisa as folklore suggests. A good place free of air resistance to test this equivalence principle is Earth's Moon, and so in 1971, Apollo 15 astronaut David Scott dropped both a hammer and a feather together toward the surface of the Moon. Sure enough, just as scientists including Galileo and Einstein would have predicted, they reached the lunar surface at the same time. The demonstrated equivalence principle states that the acceleration an object feels due to gravity does not depend on its mass, density, composition, color, shape, or anything else. The equivalence principle is so important to modern physics that its depth and reach are still being debated and tested even today.
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Do two magnets with their N S poles facing each other create a greater attractive force than a single magnet? If the force is greater doesn't that equate to greater acceleration?
If a hammer were orbiting the Earth, it would not measurably effect the tides, but the moon does. Hmmm. Why is that? Because the large object exerts greater force. Hmmm. Going back into your acceleration formulas.
As I said, you forgot that the equation has to be made for both objects, not just one, and then the result combined.
Math is great, but garbage = garbage out. Acceleration of gravity formulas must use the mass of both objects. With small objects we don't do this because it doesn't matter (measurably), but with large objects we absolutely combine the masses.
The attraction between the Earth and Moon is determined using the combined mass of both, not the mass of the Earth. This is easily understood if you think of what would happen if you pushed the Earth and Moon into one ball. That ball would have a greater gravitational attraction than the Earth right? Sure, so the same applies before they are combined.
All measurements of movement are relative to an arbitrarily chosen position.
What you are clearly doing is treating one of the masses as a parent mass, and ignoring the other.
According to your equation, if we swapped the moon and hammer as M1 and M2, the gravitational force would immediately drop off to near nothing.
Indeed, do the math.
It's like taking two identical rubber bands and stretching one to twice its unstretched length. That will produce a certain amount of tension. If you then stretch both that same amount, you'll get twice the force.
Same thing for inter-atomic attractions.
Hey, why is it always just pretty girls? Of course, at my age, I’d just as soon have pictures of pretty dogs. :)
Another big lie! Biden doesn’t have a brain....
Oh my goodness. I think I’m better at handwaving! :)
If you go back and read what AB posted, he said exactly that:
The gravitational force between two massive objects can be computedThat's the force BETWEEN any two objects - that same force acts equally on each of the two objects.Fg = G*(M1*M2)/ R2
The gravitational force would be unchanged.
Have you never heard of the "Commutative property of multiplication"?
Apparently not.
Let me introduce you to it: "Two numbers can be multiplied in either order."
This means that a room that is 10' x 15' has the same floor area as a room that is 15' x 10'.
No, per the equation, since Jupiter is roughly five times as far from the Sun as Earth and 300 times as massive, the gravitational attraction between Jupiter and the Sun is roughly 12 times that between the Earth and the Sun (300/52).
So you understand that if the Earth has more mass than the moon, that the acceleration of an object towards it is faster, but you don't understand that if the object itself has greater mass, it has the same effect.
The Moon pulls on the Earth and the Earth pulls on the moon. Together, they orbit around spot in space, aleit the Earth is much closer to that spot than the moon. The force holding them is the combined gravity of the moon and of Earth. Objects orbit at their balance point, higher masses require higher orbits or faster orbits. If the entire mass is no different than the individual atoms, why would that be? It wouldn't.
If we replace the hammer with a black hole, then the Earth is accelerated at that black hole at something greater than standard G. Just as we would be on Jupiter. Do you concur?
If you agree, then you can’t say that the mass of a falling object does not effect its acceleration, as it clearly does. All you can say is that for most objects that we care about, the difference in mass has an insignificant affect on acceleration.
Yes if the hammer were replaced by a black hole, the earth would be accelerated towards that black hole by more than the standard “G”.
That’s because one of the masses in the gravity equation is much larger and thus the gravitational attraction is greater, given equal distances.
If we replace “Earth” by “Jupiter” near the black hole it will accelerate toward the black hole at the same rate Earth does.
F=mA.
Outside of quantum mechanics, where things can magically appear out of nowhere and then disappear again, that’s the rule.
No amount of hand-waving on your part can change that.
I bid you adieu.
Amazing that you concede that increased mass matters, but then decide that it doesn’t.
I think you need to give up the lecture circuit until you can make the mass match the reality. There would be no reason to include both masses in the equation if only the larger mass mattered.
I think a pretty dog would be better. Are there really NO good looking physicists?? :)
No, I am not. There is no such thing as the "parent mass".
I am calculating the acceleration of the hammer toward the moon. If one were to "swap" the mass of moon for the hammer, one would then be calculating the acceleration of the moon toward the hammer.
It should surprise no-one that the moon is accelerated much less than the hammer. Its mass is many orders of magnitude larger.
Equation 2 in my original post computes the gravitational force between any two objects. BOTH objects are acted upon by that force.
Equation 1 in my original post shows that the effect of that force (acceleration) upon any object is inversely proportional to its mass.
Once again, do the math. The mass of the moon, or earth for that matter, may be found on the 'net. Likewise the gravitational constant ("G" in equation 2). Use 1 kilogram as the mass of the hammer. That's a heavy framing hammer, or a light engineer's hammer. Be sure to express the distance "R" in meters.
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