The Gravity Paradox: Does Mass Affect Speed?

In summary, the conversation discusses the concept of gravity and its effects on different objects. It is stated that in a vacuum, objects of different masses fall at the same speed due to the acceleration of gravity being only affected by momentum and not mass. However, when taking into account the gravitational pull of larger objects, heavier objects may fall faster due to their own gravitational pull. The conversation also touches on the idea that gravity is caused by the spinning of objects such as the sun, and the formation of bonds between atoms.
  • #1
Jarfi
384
12
So according to all if you drop a feather and a bowling ball on Earth in vacuum it falls at the same speed. So that says acceleration of gravity is not affected by mass only the momentum.

And this says that even a moon size iron ball would fall at the same speed to the Earth as a feather(in vaccuum)

And therefor if a black hole would fall on the earth(earth gets sucked in) it would suppost to fall at the same speed as the feather.

But that tells us that the speed of gravity is the same no matter what? and that is not true because we all know that when you jump at the moon it takes longer for you to fall down than if you where thrown at a neutron star or a black hole, you would accelerate extremely fast and die.

So that tells us that more mass=more/faster acceleration



So you put two neutron stars next to each other, they merge very fast(right?)

And put two Earth's next to each other, it takes more time for them to collapse

I am just confused why you say no matter what the weight is velocity is always the same but you fall at light speed(at least very fast) into a black hole...
 
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  • #2


Jarfi said:
But that tells us that the speed of gravity is the same no matter what? and that is not true because we all know that when you jump at the moon it takes longer for you to fall down than if you where thrown at a neutron star or a black hole, you would accelerate extremely fast and die.

Not at all. I think part of this misunderstanding comes from the lack of precision in statements you've heard about gravity, so here's a correct one:

In the absence of other forces, the rate at which an object falls in a gravitational field is independent of its mass or composition provided that mass is much less than the mass of the object creating the gravitational field.

To be even more precise, a bowling ball does "fall" faster than a feather. Why? Because the bowling ball "pulls the Earth up" more than the feather, so the two meet slightly quicker. In the rest frame of a bloke on the Earth, this looks like it is falling faster. But the magnitude of this effect is perilously small, something like one part in 10^24, well beyond anything we could hope to detect. Now, if you take the moon and drop it, the Earth responds significantly to the Moon's gravitational field, and this is detectable.

To move off the earth, the acceleration felt in a gravitational field (again, for objects of negligible mass) is determined by the mass of the object creating that field. So, as measured the same distance away from the object, a star would cause higher acceleration than the earth.

I could go on, and will if it enhances your understanding, but does that clear up the issue so far?
 
  • #3


Another rewording: The bowling ball falls to Earth at the same rate as the feather, but the Earth falls to the bowling ball faster than it falls to the feather. They fall toward their common center of mass, not toward the center of the earth.
 
  • #4
Nabeshin said:
Not at all. I think part of this misunderstanding comes from the lack of precision in statements you've heard about gravity, so here's a correct one:

In the absence of other forces, the rate at which an object falls in a gravitational field is independent of its mass or composition provided that mass is much less than the mass of the object creating the gravitational field.

To be even more precise, a bowling ball does "fall" faster than a feather. Why? Because the bowling ball "pulls the Earth up" more than the feather, so the two meet slightly quicker. In the rest frame of a bloke on the Earth, this looks like it is falling faster. But the magnitude of this effect is perilously small, something like one part in 10^24, well beyond anything we could hope to detect. Now, if you take the moon and drop it, the Earth responds significantly to the Moon's gravitational field, and this is detectable.

To move off the earth, the acceleration felt in a gravitational field (again, for objects of negligible mass) is determined by the mass of the object creating that field. So, as measured the same distance away from the object, a star would cause higher acceleration than the earth.

I could go on, and will if it enhances your understanding, but does that clear up the issue so far?

Mercy! I think I get it now.

A star pulls all objects at the same speed but the reason heavier objects fall faster is because they pull the star themselves more! So in the end all objects fall at the same speed but heavier objects land sooner because they pull their landing site thorwards them:)

Is my conclusion correct?
 
  • #5
russ_watters said:
Another rewording: The bowling ball falls to Earth at the same rate as the feather, but the Earth falls to the bowling ball faster than it falls to the feather. They fall toward their common center of mass, not toward the center of the earth.

Thanks man it's a good and simple law
 
  • #6


Not sure if I'm right here? but isn't Gravity merely: The sun spinning and inducing a centripetal force, While the Earth so far away making another centripetal force but weaker than the sun for its less mass and smaller surface area. This means the sun and other planets like Jupiter with their superior size and mass is what prevents the Earth getting sucked into the sun. So when we throw a small object on Earth such as a rock our centripetal force and our superior mass is what makes such a force to exist and keep our objects on the ground.

This may mean from the big bang everything exploded. everything was super heated atoms cooled down then made bonds. Those then made rocks colliding with each other pushing smaller masses further apart till there is a planetary equilibrium.
 
  • #7


All objects in a given gravitational field fall at the same rate.

But the gravitational field of a neutron star is much stronger than that of earth, so objects fall faster on the neutron star than on earth.

Not sure if I'm right here? but isn't Gravity merely: The sun spinning and inducing a centripetal force, While the Earth so far away making another centripetal force but weaker than the sun for its less mass and smaller surface area. This means the sun and other planets like Jupiter with their superior size and mass is what prevents the Earth getting sucked into the sun. So when we throw a small object on Earth such as a rock our centripetal force and our superior mass is what makes such a force to exist and keep our objects on the ground.

No. Gravity has nothing to do with rotation, and everything to do with mass (or it's energy equivalent).
 
  • #8


Jarfi said:
Mercy! I think I get it now.

A star pulls all objects at the same speed but the reason heavier objects fall faster is because they pull the star themselves more! So in the end all objects fall at the same speed but heavier objects land sooner because they pull their landing site thorwards them:)

Is my conclusion correct?

Yes...but you will only notice this effect with comparable masses. The Earth is very massive, so you will not notice this effect with everyday objects, such as a feather, a bowling ball, a car, or even a building. They just on't pull up on the Earth by any appreciable amount.

The moon, however, DOES pull on the Earth by a measurable amount. So if we dropped the moon, it would contact with the Earth faster than if we dropped a feather.
 

1. How does mass affect an object's speed?

The short answer is that the more massive an object is, the harder it is to accelerate and therefore the slower it will move. This is because mass is a measure of an object's inertia, or resistance to change in motion. The more mass an object has, the more force is needed to change its speed or direction.

2. Does gravity affect the speed of an object?

Yes, gravity does affect the speed of an object. Gravity is a force that pulls objects towards each other, and it is directly related to an object's mass. The greater the mass of an object, the greater its gravitational pull. This means that the more massive an object is, the faster it will accelerate towards the center of the Earth due to gravity.

3. Is there a relationship between mass and acceleration?

Yes, there is a direct relationship between mass and acceleration. According to Newton's Second Law of Motion, the force needed to accelerate an object is directly proportional to its mass. This means that the greater the mass of an object, the more force is needed to accelerate it at the same rate as a smaller object.

4. Can an object with more mass move at the same speed as an object with less mass?

No, an object with more mass cannot move at the same speed as an object with less mass. This is because, as stated earlier, the more massive an object is, the more force is needed to accelerate it. Therefore, in order for two objects with different masses to move at the same speed, the less massive object would need to have a greater force acting on it.

5. How does the "Gravity Paradox" relate to mass and speed?

The "Gravity Paradox" refers to the concept that objects with different masses fall at the same rate due to gravity. This was famously demonstrated by Galileo when he dropped two different sized cannonballs from the Leaning Tower of Pisa. The paradox is that even though the objects have different masses, they still accelerate at the same rate due to the force of gravity. This is because the gravitational pull is directly proportional to mass, so the greater mass of the larger object is counteracted by the greater force needed to accelerate it, resulting in the same acceleration and speed as the smaller object.

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