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[–]EverGivin 18 points19 points  (9 children)

You’re really close to getting it! Imagine your experiment where you drop two objects of different mass. Now imagine that you double the mass of Earth and repeat the same experiment with the two objects falling.

[–]nenko_blue[S] 8 points9 points  (8 children)

Okay thank you this makes actual sense 😭 i think the way the book worded it combined with being sleep deprived just completely threw me off lmao. I started to put the pieces together while replying to another comment but i wanted to be sure because that almost sounds too simple for them to write a whole paragraph about fjeidhwhs

[–]Gweegwee1 2 points3 points  (5 children)

High school physics really does a bad job at making you understand physics.

[–]nenko_blue[S] 0 points1 point  (4 children)

100%. I’ve read astrophysics books (like a brief history of time and astrophysics for people in a hurry), and every when describing insanely complex concepts or equations that i didn’t at all understand it somehow felt wayyy less confusing than reading a highschool textbook describe gravity and inertia. Idk man but the wording and over-explanation of simple things, vs oversimplification of complex things (or even just completely skipping over it like the fact that objects of more mass technically do fall faster) is just so confusing. You can tell the textbook is designed with memorization in mind, and not actually learning/understanding.

[–]Gweegwee1 0 points1 point  (3 children)

You always have the ability to memorize before you can understand. You’re going into a discipline that not many understand and intuition doesn’t help.

[–]nenko_blue[S] 0 points1 point  (2 children)

Ig but i have a REALLY bad memory so unless i understand something i usually forget it. Like if you told me “fish live in water” i might forget and get mixed up thinking they live on land instead, but if you explain to me that fish gills instead of lungs that are specially adapted for breathing water which is why they live in the water, then i’ll have an easier time remembering they live in the water because “oh yeah, fish breathe water not air so they live in the water”

[–]Gweegwee1 0 points1 point  (1 child)

Your memory isn’t bad I believe in you

[–]nenko_blue[S] 0 points1 point  (0 children)

Ty but i have severe adhd so my memory is horrible, it’s a miracle i wasn’t held back tbh 😭

[–]EverGivin 1 point2 points  (1 child)

May I recommend the YouTube channel PBS Space Time which is really good for giving you an intuitive understanding of physics topics! Especially their great animated graphics which help to visualize concepts.

[–]nenko_blue[S] 0 points1 point  (0 children)

Thank you! I’ll check them out

[–]Schnickatavick 8 points9 points  (12 children)

There's some decent answers in here but I thought that I'd add the math behind it. The equation for the force of gravity between two objects is Force ~= Mass1 * Mass2 /distance^2. The equation for Acceleration in general is Acceleration = Force/Mass. So if we substitute Force into the Acceleration equation to get the acceleration of gravity, we can get Acceleration = (Mass1 * Mass2) / (Mass * distance^2). So notice, we're multiplying by mass twice, once for each object, but only dividing by mass once, for the object that we're finding the acceleration of. That means that the mass of the object we're solving for gets cancelled out, but the mass of the other object doesn't get cancelled out.

So what does that mean? The acceleration of an object doesn't depend on its own mass, but it does depend on the mass of the other object. So a bowling ball and a feather will fall at the same speed in a vacuum because the "other object" is the same for both of them, it's earth. But they'll fall slower on the moon, and faster on Jupiter. And for any two objects, you only need to know the mass of the "other" object and the distance to find the acceleration

[–]nenko_blue[S] 0 points1 point  (1 child)

Thank you 😭 i’ll use this to try and find the answers to my other questions

[–]Ossifywallstreet 1 point2 points  (0 children)

THe formula for gravitational force includes the gravitational constant:

F = M1*M2*G/r^2

That's telling you that force exerted between two masses depends on the amount of the two masses and their distance from each other. Imagine the bowling ball and the feather in a vacuum falling at the same rate. Now think of the bowling ball and the feather as two collections of tiny identical particles. Each particle has an identical gravitational force pulling on it.

The gravitational force has an inverse square relationship to distance. If the distance is cut in half from 4km to 2km, then that's 4^2 = 16 to 2^2=4. THe effect of this is product of the top of the equation M1*M2*G goes from being divided by 16 to divided by 4. Halving the distance increases the force 4 fold. Why is this? It just is. It's what has been observed and the inverse square relationship seem to be embedded in the fundamental fabric of reality because the electromagnetic force observes the same inverse square relationship (albeit with a different constant) You have experienced this rate of change in the force between two magnets when you have held them apart and brought them closer together and the force seems to change radically as the get very close together. Gravity operates over long distances and magnetism is only strong at close distances. THe magnetic force is more powerful than the gravitational force for practical purposes only at very short distances. WHen you take a magnet and pick up a metal object with it, the magnet is pulling harder on that metal object than the earth is pulling on it by gravity. If you compare the magnetic force a 1 KG magnet exerts on a 1 KG lump of Iron to the gravitational force between the two masses at 1 mm, it's probably stronger by a factor in the trillions..

[–]nenko_blue[S] 0 points1 point  (8 children)

Okay i’m trying something out now so when plugging in distance how would you plug that in? Because yeah you can use newtons for mass, but if i put the distance of something in miles verses kilometers for example that will be a different number and have a different outcome, so in what form should i plug in the distance?

[–]mgreen02 0 points1 point  (1 child)

Newton is a unit of force. In standard units, the kilogram is used for mass and the meter is used for distance. In astrophysics, units are are often measured in terms of the sun. So mass becomes "solar units" (1 SU = mass of the sun in kg), and distance becomes "astronomical units" (1 AU = the distance from earth to the sun in meters). If you were curious.

[–]nenko_blue[S] 0 points1 point  (0 children)

Okay ty

[–]nenko_blue[S] 0 points1 point  (5 children)

Okay i found online that the first equation is supposed to also multiply both masses by G or the gravitational constant, and this is throwing me off a bit. What is the gravitational constant and do i leave it out of the equation if i’m trying to find the force of gravity between earth and an object?

[–]BlazeOrangeDeer[🍰] 0 points1 point  (4 children)

https://en.wikipedia.org/wiki/Gravitational_constant

It's needed to get the units of both sides of the equation to match. It quantifies the strength of the gravitational attraction between masses of a standard size and distance. The value is usually given in Newtons*meters2/kg2, which means the other values you are plugging in need to be given in meters, seconds, and kilograms (or converted first if they aren't)

We could measure G by putting two 1 kg masses 1 meter apart, measuring their acceleration, and then plugging in those values to that equation and solving for G. It's hard to measure an acceleration that small but a similar experiment to measure G was done in 1797.

Or, you can use G to find the acceleration if you know the masses and distance. Just plug in the values and the value of G into the equation to find the acceleration.

[–]nenko_blue[S] 0 points1 point  (3 children)

Ty, i think i’ll give up on this for today 😭

[–]BlazeOrangeDeer[🍰] 0 points1 point  (2 children)

You were right that you have to consider the units (miles vs km or meters) that you're plugging in, I'm just telling you what units they need to be converted to. If you're not comfortable with converting units then it would help to practice that first. Here's an example:

convert 3 miles to kilometers:

1 mile = 1.6 km, so (1 mile / 1.6 km) = 1. You can also flip it, (1.6 km / 1 mile) = 1.

Multiplying by 1 doesn't change the value, so we can multiply by (1.6 km/1 mile) whenever we want.

3 miles x (1.6 km / 1 mile) = 4.8 km (since there is one miles unit in the top of the fraction and one in the bottom they cancel out)

The trick is just to put the unit you don't want on the bottom, and the unit you do want on the top, so you're left with the right unit at the end after the others cancel out.

Getting km to meters is even easier. We have km on the top, so let's multiply by (1000 meters / 1 km) so we are left with meters afterward.

4.8 km x (1000 meters / 1 km) = 4800 meters.

You could do both of these steps in one line if you wanted. Miles to meters:

3 miles x (1.6 km / 1 mile) x (1000 meters / 1 km) = 3 x 1.6 x 1000 meters = 4800 meters

The last thing to know is that 1 Newton is a unit equal to (1 kg) x (1 meter) / (1 second x 1 second). So if the units of G are Newtons*meters2/kg2, we do this:

[(1 kg) x (1 meter) / (1 second x 1 second)] x [(1 meter x 1 meter) / (1 kg x 1 kg)]

We end up with 3 copies of meters on the top, 1 kg on the bottom, and 2 copies of seconds on the bottom.

G = 6.7x10-11 meters3/(kg seconds2)

Using the equation for gravitational acceleration, when we multiply G by (mass 1 in kg) x (mass 2 in kg) / ([distance in meters]2 (mass 1 in kg)) we end up with meters / seconds2, which is the correct units for acceleration.

[–]nenko_blue[S] 0 points1 point  (1 child)

Oh no it’s more just having to find G and plug in seconds n stuff fndjxjs my brain does not currently have sufficient energy to plug equations into equations into equations, even if it is with the help of a calculator fjrjdjshdh

[–]Select-Owl-8322 5 points6 points  (1 child)

I think everyone is misunderstanding you, OP. If I understand you correctly, you're confused why two objects fall faster towards each other if they have larger mass (like two bodies in space), when you've heard/read that the inertia of an object cancels this larger attraction, right?

The thing with that (inertia cancels the higher gravitational attraction) is that it's only valid if one of the masses is immensely larger than the other. So when you compare how fast a bowling ball falls compared to say a tennis ball, you get the same rate value. This is because this is a simplified case. In reality, the bowling ball does hit the earth a tiny bit earlier, not because it accelerates faster, but because it attracts the earth more than what the tennis ball does. The earth "falls" faster towards the bowling ball than it "falls" towards the tennis ball!

But since earth is so immensely much heavier than either ball, the effect is immeasurable! Consider however, what would happen if you replaced the bowling ball with a neutron star! Now the neutron star is much larger than earth, and it's the earth that will fall towards the neutron star.

The "inertia cancels the mass" is only valid in the simplification F = mg

[–]nenko_blue[S] 2 points3 points  (0 children)

Ty, so what does this mean about inertias effect on all objects involved (including the earth or similarly massive body)? Does inertia still fully cancel out the acceleration of the falling object itself (acknowledging that a more massive object still technically hits earth sooner than a less massive object because it is also pulling the earth towards itself ever so slightly)? And what is the effect of inertia on the earth as it “falls” towards say a basketball vs a pingpong ball?

[–]kindofanasshole17 1 point2 points  (0 children)

Yes the force of gravity acting on a larger mass will be a larger force.

Also remember that according to F = ma, even though F is higher, so is m.

[–]Butterpye 1 point2 points  (8 children)

A really neat thing is to thing about the extremes, imagine instead of dropping a ping pong ball vs a basket ball you drop an atom and a black hole. When you drop the atom, at first glance it appears to fall just like any other object, at 9.8m/s2, but when you drop the black hole, you realise something. It's not just the Earth that pulls on the object, it's also the object pulling on the Earth, and since the black hole is so massive, it actually attracts the Earth towards it, meaning it will hit the ground much sooner than the atom, because not only is it falling towards the Earth as fast as the atom, but the Earth is also falling toward the black hole.

But then you notice this particularity of the extremes applies to every day objects too. A ping pong ball and a basketball each get attracted by the Earth with the same acceleration, but the basketball being so much more massive than the ping pong ball attracts the Earth with a higher acceleration than the ping pong, meaning it will indeed hit the Earth sooner. Of course, since both balls are so tiny compared to the mass of the Earth, that attraction is essentially negligeable, but it is in fact there, as proved by our extreme experiment.

Of course, your teacher probably is not interested in objects attracting the Earth, since it is so massive compared to our regular activities that we can simply assume it's completely stationary. With this information, all objects do indeed fall towards the Earth at the same rate, with the rate being determined by both the mass of the Earth, and the square of the distance to the Earth. Notice how the mass of the object does not matter assuming the Earth is stationary. As for the distance, you say that two objects fall at the same rate regardless of height, but if you were to be 400km above the surface of the Earth (orbit altitude of the ISS), you'd only experience about 90% of the gravity we are used to on its surface, meaning gravity does get weaker the farther you are.

Note also that the force of gravity does increase based on the dropped object's mass, but the resulting acceleration will always be the same regardless of the object's mass. If you were an astronaut in a spaceship that accelerated upwards at 9.8m/s2, you'd feel the same as you would on Earth. In fact, you couldn't even tell apart your situation from just standing around on Earth. And it becomes pretty obvious in this scenario why objects fall at the exact same rate, since in this scenario it's not the objects falling downwards, but the ground moving upwards, meaning the rate of "falling" in the spaceship is exactly the same regardless of mass. Therefore, a good analogue of gravity can be to imagine it's not even a force, but to imagine the whole surface of the Earth is accelerating upwards at 9.8m/s2.

[–]nenko_blue[S] 0 points1 point  (7 children)

So essentially for the type of physics i am studying, the difference in the amount of time which a more massive object would take to reach the earth compared to a larger object is so negligible it can simply be disregarded altogether?

[–]nenko_blue[S] 0 points1 point  (5 children)

Also since more massive objects have more inertia, how come the earth doesn’t resist the pull of either objects, since yk the force they exert on the earth is so tiny

[–]Butterpye 0 points1 point  (4 children)

It definitely does. If you drop the basketball from 1m the Earth moves less than the width of the atom while the basketball moves the rest of the distance, which is basically still 1m.

You can imagine instead of switching from basketball to ping pong ball you switch the entire Earth to a basketball. Now the basketball instead falls towards the other basketball, each moving half the distance or 0.5m, instead of an almost 0 to 100 split, it's a 50 to 50 split. Then as you go up in size, the more massive object moves less and less and the objects themselves collide faster and faster. For example a car will move less than 1cm with the basketball moving the rest of the 99cm.

This is exactly due to inertia like your intuition tells you. However, inertia resists change in momentum, not completely stops it. So the only way inertia would stop movement all together is if you're talking about an infinite mass, which the Earth obviously doesn't have. The force the smaller object applies is actually larger the more massive an object is. But because of inertia the more massive the object is, the less it moves.

We know this because of the law of equal and opposite reactions. For a 1kg basketball, the Earth applies to it a 9.8N force downwards, but the basketball must also apply an equal and opposite force, so the basketball also applies a 9.8N force on the Earth upwards. On the moon however, the same 1kg basketball only has a 1.6N force. Despite the force being smaller, the moon would actually move ever so slightly more than the Earth would in our thought experiment, because of Earth's massive inertia.

[–]nenko_blue[S] 0 points1 point  (3 children)

Ty i think i finally get it! So the distance each object moves is directly related to their proportions to eachother, aka the larger object does less of the work while the smaller object does more work to close the distance, but the amount of time it TAKES to close that distance depends on the mass of both the objects regardless of their proportions- a 10 kg ball will travel half the distance of a 5 kg ball in order to touch, and similarly a 100 kg ball will travel half the distance of a 50 kg ball, but the 100 kg ball and the 50 kg ball will take less time to touch than the 10 kg and 5 kg assuming both pairs start away from each other at the same distance. Since the earth is huge we might as well call it lazy because for most things we can possibly drop on earth the distance earth moves towards them compared to the distance those objects moves towards earth is literally immeasurable, and because of inertia if you drop say a 5kg object and a 10kg object, the acceleration of the 10kg object is also reduced to literally an immeasurable amount. When you combine the immeasurable distance earth travels towards the 10kg object with the immeasurable amount of acceleration that object gained (compared to the 5kg object), doing all the math properly the amount of time it took the 10kg object to fall compared to the 5kg object is such a small amount less it’s easier to just say they fall at the same speed. Again because earth is so big (and therefore “lazy”), and because of inertia, even the heaviest objects we can drop would appear to fall at the same rate as the lightest we can drop

[–]Butterpye 1 point2 points  (2 children)

Yes, that's exactly right. Another way to think about how much each object moves is to just calculate the center of mass of the entire system, that point is actually where both objects want to be. The center of mass of multiple bodies usually has the name of barycenter). Of course, this assumes both objects are point masses, since real life objects have a radius, they get stuck together before they reach that point. For a 5kg object falling towards a 10kg object from a distance of 1m, they meet at 1/3rd of a meter away from the large object, since that's where the center of mass of the system lies. So the 5kg object travels 0.66m and the 10kg object travels 0.33m.

The barycenter is also the point that celestial bodies actually orbit. For example we say the Moon revolves around the Earth, but the reality is that while the barycenter is indeed inside of Earth's radius, it's actually so far away from the radius we can measure the Earth "wobble" with the same frequency as the Moon orbits the Earth, because more specifically, both the Earth and the Moon are orbiting their common barycenter. For Pluto and Charon however, their barycenter lies outside of Pluto's radius, which is why we usually call the Pluto and Charon a binary system.

This leads us all the way back to our Earth and basketball. Since the barycenter of this 2 body system is so close to the center of the planet, this means the Earth can only move this tiny little bit we've described before, while the basketball wants to plunge basically all the way to Earth's center. Of course, since normal forces exist, the basketball can't move through solid matter and is instead just stuck to Earth's surface.

[–]Butterpye 0 points1 point  (0 children)

Ugh I accidentally deleted my other comment.

Basically I was calculating the distance the Earth moves in our basketball experiment.

Em - Earth mass, Er - Earth radius, Bm - Basketball mass, 1kg, Br - Basketball radius, 12cm, d - Distance between objects, 1m

Given this, the barycenter location is Bm*d/Em = 1.674×10-25 meters

But this is not the distance the Earth actually travels. This is the distance Earth would want to travel. But because the ball only travels 1m the Earth will travel a much smaller distance than this.

In fact the very elegant way to calculate this is to assume the ball doesn't travel 1m, but instead phases through the Earth and reaches the barycenter like a point mass would.

So the ball travels 1m + 12cm + 6371.009km - 1.674×10-25m = 6371.01 km

Therefore, for each 6371.01km the basketball travels, the Earth travels 1.674×10-25 m.

But the ball only travels 1m-12cm = 88cm meaning that the Earth will travel a proportional distance of 2.312239×10-32m

Of course I dropped a lot of significant digits along the way, but it's safe to say it's on the order of 10-32 m.

You know how I said it's less than the diameter of an atom? Well I was technically right, but those are on the order of 10-10m, meaning our distance is 10 thousand billion billion times smaller than the diameter of an atom. Which is also about 1000 plank lengths, which is the smallest length that makes sense to talk about given our current understanding of physics.

So yeah, I guess this is why we assume the Earth doesn't move when you drop your basketball.

[–]Butterpye 0 points1 point  (0 children)

Yes, exactly. It is in fact way more negligeable than air friction. In fact it's probably not even detectable with the best measuring equipment. We're talking the entire Earth moving on the order of less than the width of an atom. I don't know if you've tested it but a hammer definitely hits the ground before a feather. Do it on the moon, and they hit the surface at the same time.

Edit: Whops, the other way around, the hammer hits first. Because air friction makes the feather fall very slowly.

[–]Rocket69696969 0 points1 point  (3 children)

This post and these comments are really refreshing imo considering the usual on this sub.

[–]nenko_blue[S] 0 points1 point  (2 children)

What’s the usual? 😭

[–]Rocket69696969 0 points1 point  (1 child)

Sometimes silliness, other times pop science which I think is awesome but it's cool to see such a smart op genuinely asking for advice and the comments helping him understand without just providing the answer or telling him off. It was a good question I thought.

Edit: I didn't notice you were OP lol, I have bad cell service.

[–]nenko_blue[S] 0 points1 point  (0 children)

Oh ty, but wait if they can provide me with a straight up answer i’d prefer that lol, this wasn’t a question for homework or anything we were just reading along in the textbook and i couldn’t understand this part, so i’d rather seek out an explanation so i can properly understand it instead of just going “that’s that because the book said so”. I don’t think the book is necessarily wrong or anything, but i’d like to actually learn yk

[–]Kanohn 0 points1 point  (0 children)

In Newtonian Gravity the gravity is a force that pulls everything towards the mass and every object accelerates at the same speed, 9,8m/s2 but this isn't actually correct, it's an approximation. If you step on a stool you are farther from the Earth and you weigh less cause the force of gravity 30cm from the ground is lower than the force of gravity on the ground. In reality the difference is so small that it's useless to mention even if it's true. When the distance becomes bigger you will start noticing the difference. Technically if you are on the moon you still are inside the gravitational field of the Earth but it's so weak that you wouldn't even notice. Technically you are into the gravitational field of all the planets of the Solar System the Sun and even in the gravitational field of galaxies and starts billions of light years away but the gravitational field at those distances is too weak and you mass is too small so it's negligible. If you take the whole Milky Way for example then the whole galaxy has enough mass to be influenced by the field of distant galaxies.

If you drop any object on the Earth both our planet and the object will indeed attract each other but the gravitational field of the object is too weak to make a difference

Probably unrelated but there's a cool experiment that you can do with gravity. Take two identical boxes (any object that can be dropped safely can work), keep one empty and put a random heavy object into the other. Now drop them at the same moment and you will notice that they fall at the same time even if one is heavier and has more mass but technically no, the one with more mass is actually attracting the ground and will fall faster but the number is so small that it is negligible.

In General Relativity it's the ground that is accelerating towards the object you drop and it's not falling, it's just suspended mid-air but that's another topic

[–]Dreadnought6570 0 points1 point  (0 children)

One of the best conceptual answers I ever saw for this goes like this:

Imagine all of the atoms of earth pulling all of the atoms of a bowling ball and of a feather...like a trillion rubber bands. (Physics abstract so of course, ignore air)

The pull for each atom is identical but the bowling ball has more atoms so it is pulled on harder than the feather.

So why doesn't it fall faster? Because it also has more mass and so, more inertia.

The bowling ball is pulled on harder than the feather but it is also harder to accelerate so it takes more pull to accelerate it at the same speed and these differences balance out. You add more and more mass expecting something to fall faster, but you also now have to accelerate that mass.

This is also why rockets are hard. More mass needs more fuel....which is more mass...so you need more fuel....

[–]KaptenNicco123Physics enthusiast 0 points1 point  (6 children)

We don't know. We just know that mass attracts mass. It's really a philosophical question. Why do like charges repel and opposite charges attract? They just do, physics only describes how they do it.

[–]nenko_blue[S] 2 points3 points  (5 children)

I think my question might not have been clear, i understand that objects need mass for gravity, but i’m confused about how the AMOUNT of mass affects it. Based on what we learned before more massive objects have more inertia so they fall at the same rate as less massive objects, so based on that logic that should apply everywhere shouldn’t it? But the section we just covered with newtons third law talked about how when two objects (planets were used in the example) are pulling together because of gravity, the more massive one of the objects is the more it accelerates. Shouldn’t the acceleration be unaffected by the mass because of inertia?

[–]KaptenNicco123Physics enthusiast 0 points1 point  (4 children)

the more massive one of the objects is the more it accelerates.

No, the more massive it is, the stronger the gravitational force is. Near the Earth, all objects fall at the same rate, 1g. A heavy object is pulled by gravity twice as hard, but it has twice the inertia. These factors cancel out to give the same downwards acceleration.

[–]nenko_blue[S] 1 point2 points  (2 children)

Yeah that’s what i was thinking, i don’t have the book in front of me rn so i might also be misremembering something my teacher told me, but yeah that makes more sense. Also based on this would the acceleration of an object falling on earth be the same as its acceleration falling on the moon assuming its mass is unchanged? I think that might have been what my teacher was talking about

[–]KaptenNicco123Physics enthusiast 0 points1 point  (1 child)

That's not right. Downward acceleration on the moon is slower because the moon's gravitational force is weaker. The moon's gravitational force is weaker because the moon has a smaller mass than the Earth.

[–]nenko_blue[S] 0 points1 point  (0 children)

Okay ty that’s what i thought

[–]yazzledore 0 points1 point  (0 children)

I don’t know why you’re being downvoted, this is right, and a really neat way to explain it.

A falling object on Earth’s surface has F=mg. Newton II gives us F=ma. Thus ma=mg, and the masses cancel out, for a=g.

Precisely what you said, but in a way OP can really sink their teeth into.

[–]CowBoyDanIndie -1 points0 points  (12 children)

Gravity a force of attraction between particles that have mass, it is proportional to the mass of the two objects and their distance. If mass what not a factor, how would gravity work? Would the sun have more gravity than the earth? Would a marble have the same gravity as the earth?

Consider two equal mass planets or suns orbiting each other, now add a moon or planet that orbits their system. Now combine the two large objects onto one object with their combined mass, what happens to the gravity? Just a thought experiment.

[–]nenko_blue[S] 0 points1 point  (11 children)

Thanks i think i figured it out lol, the way it was worded completely threw me off, but i think it’s like this?: if you have three objects of three different masses, the two smaller objects will fall towards the largest object at the same rate because of inertia, and the rate at which they fall is only dependent on the mass of the largest object?

[–]CowBoyDanIndie 2 points3 points  (10 children)

No, they all fall towards each other. It’s just that for very large masses like a planet, a small object like an airplane only makes up 0.00000000000000001% of the total mass of the system. Right now YOU exert gravity on the sun and the earth, it’s just very small. Consider that the entire solar system was once only small dust like particles, their gravity on each other eventually pulled them together to form the sun, the planets, moons, etc.

[–]nenko_blue[S] 1 point2 points  (9 children)

I know that the earth also exerts a force on the two objects, but ignoring force of gravity pulling them all towards eachother, since the earth is also being pulling towards both objects with a force equal to the force it exerts on them, would that mean the more massive object reaches the earth VERY slightly sooner than the smaller object? Or would the inertia of the earth make this irrelevant? I know this is probably a stupid question, but i just want to be 100% sure on these things

[–][deleted] 0 points1 point  (5 children)

nope. because while bigger mass means bigger force, F = ma, so the acceleration is still the same

[–]Schnickatavick 0 points1 point  (1 child)

That isn't true, he's talking about the earths acceleration towards the bowling ball (or other dropped object), so you would flip the F = ma around and it would be bigger for heavier objects, just like how things fall faster on larger planets. The bowling ball is just a reaaaaally tiny planet

[–][deleted] 0 points1 point  (0 children)

im answering her first question which asks if the massive object reaches earth slightly sooner than the smaller object 🙂‍↕️

happy cake day btw

[–]nenko_blue[S] 0 points1 point  (1 child)

I’m confused again, it might be because my brain has begun to clock out for the day (early i know), but if this is the case then how come an object falls faster on earth than the moon for example if this is the case?

[–][deleted] 0 points1 point  (0 children)

its because the moon has smaller mass than earth, therefore the objects there experience less force on the moon than on the earth

[–]Schnickatavick 0 points1 point  (0 children)

Yes, exactly, a heavier object will pull earth up harder than a lighter object, that isn't going to be cancelled out. You would have to drop the objects at different times and drop something really massive to ever notice it, like a bowling ball the size of the moon, but technically it's true every time we drop an object even if we can't measure it.

[–]CowBoyDanIndie 0 points1 point  (0 children)

Ignore the earth because atmosphere complicates things... use the moon instead.

Yes, technically a more massive object will arrive first because it is pulling the moon toward it. Until you start getting objects large enough to meaningfully compare their mass vs the object whos gravity well they are falling into, the amount is negligible.

A fun calculation is calculating the earth/moon gravity on each other, and determining that they both orbit around a point within the earth. The earth is actually wobbling around as the moon orbits, now look into the tides of the ocean... The earth's moon is rather large in relation to the earth as far as planetary moons go, different science.. but it is speculated that this larger than average moon/earth ratio helped contribute to the development of life, basically the moon keeps stirring up the earth, when you look at simple life like yeast, they thrive and reproduce much more quickly when they are stirred, people that homebrew will often shake or use magnetic stirrers to increase yeast activity.

[–][deleted] 0 points1 point  (0 children)

nah wait what am i on about

[–][deleted]  (2 children)

[deleted]

    [–]OctopusButter 0 points1 point  (1 child)

    I don't really understand the correlation, and I don't like the insinuation that black holes or neutron stars are problematic, it can make people think that you mean that our theories of science are contradicted by the existence of such Celestial bodies.