How come when I throw a ball 90 degrees to top inside a moving bus it comes back...

[aleeboy]

This thread

[Bigdumogre]

[AlexSays]

Air resistance effect on the ball will generally be negligible, and the ball will come down to you (I don’t mean exactly, just that it comes down to you and you catch it)- I mean did you see the video I posted above?

Have you ever tried this as a passenger in, say, a golf cart , and just tossed a golf ball up- does it fall way away from you?

Depends on the ball, if it's a golf ball (relatively dense, low surface area) then likely the air resistance is negligible. Same with your medicine ball example

Tennis ball or beach ball would be a very different story.

In short the OPs question was if the ball doesn't come back on a bike then why, the answer would be that obviously the air resistance was adequate and the ball the correct constitution to be left behind whereas in the bus that is not the case as the air resistance is the same as if you were standing still

[numberguy12]

Depends on the ball, if it's a golf ball (relatively dense, low surface area) then likely the air resistance is negligible. Same with your medicine ball example

Tennis ball or beach ball would be a very different story.

In short the OPs question was if the ball doesn't come back on a bike then why, the answer would be that obviously the air resistance was adequate and the ball the correct constitution to be left behind whereas in the bus that is not the case as the air resistance is the same as if you were standing still

Actually with a tennis ball in the 10 mph test above it comes back to him and he catches it....this is throwing the ball pretty high too. A shorter, normal toss of a tennis ball on say a bike, or golf cart, in normal conditions, will still come to you.

The point I was criticizing above is this belief the ball would somehow instantly zoom away when thrown from, say a bike (no, it has the inertia from the bike, subject to air resistance).

[iwant2beswole]

physics not even once

[MiscInformed]

Yes busses have their own gravitational pull and atmosphere.

There's no such force as gravity though.

100% srs.

Gravity is how our brains perceive the curving of space. Because our brains cannot comprehend this intuitively, we perceive a "force" to explain and predict why objects move as they do. We can model and predict these effects within inertial frames using Newtonian physics, but those equations aren't based on a model of what's actually happening.


https://www.youtube.com/watch?v=nR9nE1TalZc

[15thPeak]

There's no such force as gravity though.

100% srs.

Gravity is how our brains perceive the curving of space. Because our brains cannot comprehend this intuitively, we perceive a "force" to explain and predict why objects move as they do. We can model and predict these effects within inertial frames using Newtonian physics, but those equations aren't based on a model of what's actually happening.


https://www.youtube.com/watch?v=nR9nE1TalZc

Why is this even argued? Everyone says the force due to gravity.

[AlexSays]

Actually with a tennis ball in the 10 mph test above it comes back to him and he catches it....this is throwing the ball pretty high too. A shorter, normal toss of a tennis ball on say a bike, or golf cart, in normal conditions, will still come to you.

The point I was criticizing above is this belief the ball would somehow instantly zoom away when thrown from, say a bike (no, it has the inertia from the bike, subject to air resistance).

Oh no I agree that's garbage, it's more it just won't fall back to the exact same relative point it was thrown from

[MrBourbon]

Yes busses have their own gravitational pull and atmosphere.

This is a vast oversimplification of the internal physics of busses, but I guess it works for the purpose of this discussion.

[trump17x6]

because velocity vectors add you down syndrome fuktard

[trump17x6]

There's no such force as gravity though.

100% srs.

Gravity is how our brains perceive the curving of space. Because our brains cannot comprehend this intuitively, we perceive a "force" to explain and predict why objects move as they do. We can model and predict these effects within inertial frames using Newtonian physics, but those equations aren't based on a model of what's actually happening.

[youtube]nR9nE1TalZc[/youtuberl]

It's still a force. The force is due to the curvature. It's a misconception that it isn't a force. It's directly experienced as a force. Perhaps it is qualitatively different from the other forces in that we have a very clear geometric perspective for it, but it is still very much a fundamental force and shares many properties with the force associated with our other favorite massless gauge boson, the photon. That the speed of gravity and light in a vacuum are both the same is highly suggestive that there is an associated massless graviton. We have detected gravitational waves and we know their propagation speed through space.

[DeputyDong5]

It's still a force. The force is due to the curvature. It's a misconception that it isn't a force. It's directly experienced as a force. Perhaps it is qualitatively different from the other forces in that we have a very clear geometric perspective for it, but it is still very much a fundamental force and shares many properties with the force associated with our other favorite massless gauge boson, the photon. That the speed of gravity and light in a vacuum are both the same is highly suggestive that there is an associated massless graviton. We have detected gravitational waves and we know their propagation speed through space.

this is wincel

[AlexSays]

This is a vast oversimplification of the internal physics of busses, but I guess it works for the purpose of this discussion.

Have long considered taking a class in bus physics.

can imagine the lessons just going round and round

[Merc009]

Came here to drop some knowledge,

Leaving mind blown at the fact that busses have their own gravity

[MiscInformed]

It's still a force. The force is due to the curvature. It's a misconception that it isn't a force. It's directly experienced as a force. Perhaps it is qualitatively different from the other forces in that we have a very clear geometric perspective for it, but it is still very much a fundamental force and shares many properties with the force associated with our other favorite massless gauge boson, the photon. That the speed of gravity and light in a vacuum are both the same is highly suggestive that there is an associated massless graviton. We have detected gravitational waves and we know their propagation speed through space.

Einstein disagrees. Thinking of gravity as a force is misunderstanding the nature of space and time. If I'm in Africa at the equator and you're in Latin America at the equator, and we both start walking exactly due north, eventually we'll be close enough to shake hands (when we get close to the north pole), even though we started thousands of miles apart. Was there a force acting on each of us that "pushed" us closer to each other? No. We both walked along straight paths. It was the paths (on a curved surface) that were responsible for bringing us together so we could shake hands. So gravity is sorta like that. It's not a real force that acts objects and gravity waves are just our brains way of interpreting perturbations in the curvature of space and time that we can't otherwise explain (yet!).

The graviton is still just a hypothetical particle.

https://www.news.ucsb.edu/2020/019817/hunt-gravitons

[trump17x6]

Einstein disagrees. Thinking of gravity as a force is misunderstanding the nature of space and time. If I'm in Africa at the equator and you're in Latin America at the equator, and we both start walking exactly due north, eventually we'll be close enough to shake hands (when we get close to the north pole), even though we started thousands of miles apart. Was there a force acting on each of us that "pushed" us closer to each other? No. We both walked along straight paths. It was the paths (on a curved surface) that were responsible for bringing us together so we could shake hands. So gravity is sorta like that. It's not a real force that acts objects and gravity waves are just our brains way of interpreting perturbations in the curvature of space and time that we can't otherwise explain (yet!).

The graviton is still just a hypothetical particle.

I'd ask what we mean by force then. Just because gravity has a geometric picture associated with it doesn't make it any less "real". One of the key ideas behind GR is that in reality, there is no such thing as a true inertial frame. If that's the case, we really need to look more at what we mean by "force" when we argue gravity somehow isn't one. Classically, a force is anything that causes a mass to accelerate. Gravity is thus an apparent force. It's no less real to any observer. We may know it is due to the curvature of spacetime, but that doesn't make it any less "real".

The graviton may be hypothetical, but it sure would be weird if there weren't one.

For your example, there was an apparent force acting on you the entire time, gravity. It's really a philosophical question of intrinsic vs extrinsic geometry. It's the same way you can embed a Riemann surface into a higher dimension and look at it globally or you can stick only to the surface coordinate charts and get the same answer locally.

Locally, gravity is a force. Globally, it's simply a consequence of the curvature of spacetime. But a caveat is that the local picture is somehow the most "real". It is the local picture that gives you what is happening at the very small scales and what the observer directly sees. (Still an open question how to reconcile this with GR btw.) The big picture washes out all the details.

[elterrible987]

What

you would apply a force/acceleration in the verticle direction, lowering your speed/energy at impact with the ground compared to doing nothing. Except timing it would be impractical in the real world.

source: tier 1 intelligence

[bannedjpg]

in on thread of miscers trying to prove flat earth wrong

[elterrible987]

There's no such force as gravity though.

100% srs.

Gravity is how our brains perceive the curving of space. Because our brains cannot comprehend this intuitively, we perceive a "force" to explain and predict why objects move as they do. We can model and predict these effects within inertial frames using Newtonian physics, but those equations aren't based on a model of what's actually happening.


https://www.youtube.com/watch?v=nR9nE1TalZc

that is just semantics and a waste of time. your weight and gravity is a real acceleration. its not the same as plain inertia moving in a direction. That guy saying remove the floor and your inertia would bring you down to the center of the earth is misleading, intertia is tendency to move at a constant speed, you have a real acceleration towards the center of the earth and without energy to counter it, you arent moving and in statics without something strong enough to support your weight, its falling. Changing reference points or arguing semantics is a meaningless try hard exercise.

[trump17x6]

you would apply a force/acceleration in the verticle direction, lowering your speed/energy at impact with the ground compared to doing nothing. Except timing it would be impractical in the real world.

source: tier 1 intelligence

First of all, an elevator in free fall will send you floating above the floor of the elevator. You won't actually be able to push off of the floor. Second of all, you lack the quads to make that kind of push to accelerate enough to counter the velocity you would have gained from falling a few stories. So, you're going to go splat.

Sorry, but Fast and the Furious physics are not real tea.

[elterrible987]

Einstein disagrees. Thinking of gravity as a force is misunderstanding the nature of space and time. If I'm in Africa at the equator and you're in Latin America at the equator, and we both start walking exactly due north, eventually we'll be close enough to shake hands (when we get close to the north pole), even though we started thousands of miles apart. Was there a force acting on each of us that "pushed" us closer to each other? No. We both walked along straight paths. It was the paths (on a curved surface) that were responsible for bringing us together so we could shake hands. So gravity is sorta like that. It's not a real force that acts objects and gravity waves are just our brains way of interpreting perturbations in the curvature of space and time that we can't otherwise explain (yet!).

The graviton is still just a hypothetical particle.

https://www.news.ucsb.edu/2020/019817/hunt-gravitons

That is endless try hard chit.

You can frame things in many ways. You can model things in many ways. When they build skyscrapers they newtonian physics with empirical constants. They neglect einstein physics. Guess what it still works.

I can be a try hard know it all and say the bold is wrong, there is a force pulling you together, gravity of both the people techincally pulls you two together even though its imperceivable (though not immeasurable) in the real world and not enough to overcome friction if you both stopped moving. So what.

[elterrible987]

First of all, an elevator in free fall will send you floating above the floor of the elevator. You won't actually be able to push off of the floor. Second of all, you lack the quads to make that kind of push to accelerate enough to counter the velocity you would have gained from falling a few stories. So, you're going to go splat.

assumption, you fall at the same rate as the elevator. You may or may not be in contact with the elevator floor.

i didnt say it was practical, i said it was possible in theory


and actually look at the space x rocket landing on the barges. It really follows the same principle. It "falls" to earth then uses a booster rocket in the opposite direction to slow down its fall to a speed that doesnt destroy the rocket when it impacts with the barge.

source: tier 1 intelligence.

[trump17x6]

assumption, you fall at the same rate as the elevator. You may or may not be in contact with the elevator floor.

i didnt say it was practical, i said it was possible in theory

It's not even possible in theory because anyone with those kind of quads would be able to jump multiple stories high. We're also ignoring the part where you slam your head on the ceiling and then go back down.

[elterrible987]

It's not even possible in theory because anyone with those kind of quads would be able to jump multiple stories high. We're also ignoring the part where you slam your head on the ceiling and then go back down.

your weight doesnt increase when you are falling. you are confused with the elevator accelerating upwards, where you would be pressed against the floor and feel like you weigh more than you do.

you and the elevator falling at the same rate, you could easily push off it, IF your legs were in contact with it, which making good contact with it would be the problem.


look at astronauts in the shuttle, how effortlessly they can push off the walls, they are in free fall like you would be. You could effortlessly push off the elevator floor.

[trump17x6]

your weight doesnt change when you are falling. you are confused with the elevator accelerating upwards, where you would be pressed against the floor and feel like you weigh more than you do.

you and the elevator falling at the same rate, you could easily push off it, IF your legs were in contact with it, which making good contact with it would be the problem.

If you and the elevator fall at the same rate and are connected, and your legs are in contact with it, you can push off it, but if the elevator starts to fall, in real life, you are going to become apparently weightless in free fall, and you will feel like you are being shoved upward due to your inertia. Chances are good that you won't even be firmly in contact with the ground. If you are able to be in contact with the ground, you could jump, but if you had to accelerate with enough leg strength to counteract the acceleration due to gravity and accelerate enough to rapidly reverse your velocity so that it would be zero at landing, you're also probably going to jump into the ceiling of the elevator, hit your head, and end up in free fall again.

Spacex example requires a thruster. You can see why. Jumping is different from the thruster. If you had rocket shoes that shot material out to give you a lift, that gets rid of needing to be in contact with the ground. There's still the issue of having enough upward force to counteract the downward velocity you have along with the issue that if you have that much force, it's only a small amount of time before you slam into the ceiling.

[trump17x6]

your weight doesnt increase when you are falling. you are confused with the elevator accelerating upwards, where you would be pressed against the floor and feel like you weigh more than you do.

you and the elevator falling at the same rate, you could easily push off it, IF your legs were in contact with it, which making good contact with it would be the problem.


look at astronauts in the shuttle, how effortlessly they can push off the walls, they are in free fall like you would be. You could effortlessly push off the elevator floor.

An astronaut can get stuck if he doesn't have something to push off of or throw away in the opposite direction. Srs. It's hard to move down once you're in free fall. If your feet leave contact, tour is over unless there is something you can grab to force yourself downwards. I suppose you could launch something up to go down to the floor.

[elterrible987]

If you and the elevator fall at the same rate and are connected, and your legs are in contact with it, you can push off it, but if the elevator starts to fall, in real life, you are going to become apparently weightless in free fall, and you will feel like you are being shoved upward due to your inertia. Chances are good that you won't even be firmly in contact with the ground. If you are able to be in contact with the ground, you could jump, but if you had to accelerate with enough leg strength to counteract the acceleration due to gravity and accelerate enough to rapidly reverse your velocity so that it would be zero at landing, you're also probably going to jump into the ceiling of the elevator, hit your head, and end up in free fall again.

Spacex example requires a thurster. You can see why. Jumping is different from the thruster. If you had rocket shoes that shot material out to give you a lift, that gets rid of needing to be in contact with the ground. There's still the issue of having enough upward force to counteract the downward velocity you have along with the issue that if you have that much force, it's only a small amount of time before you slam into the ceiling.

I know all this. Im tier 1. I said it wasnt practical in the real world from the get go.

Also counteracting acceleration from gravity with your leg strength... idk why you are still stuck on that. Go jump right now, just from the ground. Boom you just counter acted the acceleration of gravity. You dont need massive quads, that is what happens anytime anyone has jumped ever.

[trump17x6]

I know all this. Im tier 1. I said it wasnt practical in the real world from the get go.

Also counteracting acceleration from gravity with your leg strength... idk why you are still stuck on that. Go jump right now, just from the ground. Boom you just counter acted the acceleration of gravity. You dont need massive quads, that is what happens anytime anyone has jumped ever.

That's not the problem. The problem is counteracting it enough to reach velocity zero at landing. That is equivalent, if you had been falling for several seconds to a very very strong jump. Let's assume you fall from rest. You fall for 4 seconds. Your velocity is now -4g. Let's say you have the ability to jump now. You want to jump so that after the last 0.5 s, your velocity will be zero. You'd need to supply an 8 g jump to do it. That's like Superman bro. And while your velocity would be zero relative to the ground at impact, there is the slight issue of you slamming into the ceiling at a pretty high speed, head first.

[numberguy12]

you would apply a force/acceleration in the verticle direction, lowering your speed/energy at impact with the ground compared to doing nothing. Except timing it would be impractical in the real world.

source: tier 1 intelligence

Your post made it seem like you could just casually avoid death by jumping at the correct time in an elevator freely falling. In reality, especially if the elevator were dropping a good distance, this is not typically the case, and while the effect of your jump does lessen the impact, it is not going to do it to that much of a degree. This is not to mention the problems with “jumping” off the ground while in free fall anyway.

I believe Mythbusters did an episode on this concept.