Gravity Definition and 1000 Threads

According to general relativity, gravity is not a force, however it is referred as one of the four fundamental forces. This seems like a contradiction.

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The slope of the v^2 vs h graph is g

If we have a conservative vector field, then we can describe it as ##\textbf{F}=\nabla\phi## where ##\phi## is some potential. This here is the derivation of Newtons law of gravity: Where ##\nabla u## is the gravitational potential. If we were to ignore it as a gravitational field, why is it...

Determine the volume of the shaded area around the Y-axis by using the theorem of Pappus Guldinus, where value of R = 143,3 cm. a) Determine the area of the shaded section. b) Determine the center of gravity of the shaded section. c) Detrmine the volume by using the theorem of Pappus Guldinus...

It was just a conceptional question. I thought that the positive work is done while it arises and negative work is done while it falls. For the effect of air resistance, the work done on each case would be less than the work done in absence of air resistance. Is there any other things that I can...

I don't even know where to start... could you please show me step by step

What gravity is, as pointed out by Newton and Einstein, is still a mystery. Adding to that conundrum is dark energy which continues to inflate the cosmos. Both Newton and Einstein, and every one else as far as I am able to discern, assume that gravity works by drawing massive bodies together...

I made a sample ‘test run’ with one, two, three and four weights of equal mass. Wheel number 1: one weight placed on the rim. Wheel number 2: two equal weights placed opposite to each other at 180 degrees angle, (‘diameter configuration’) Wheel number 3: three equal weights placed at 120 degree...

Neil deGrasse Tyson states that "dark matter exerts gravity according to the same rules that ordinary matters follows" How do we know this? If we have no idea what dark matter is, how can we say how it behaves? How do we know that a single "molecule" of the stuff doesn't weigh as much as the...

It's often said that you don't feel Earth rotation because the gravity acts against the centrifugal force. Of course this is true but also your body is turned around once each 24 hours. So I wonder on a planet which is rotating once each 3 seconds and has same g=9,81: Would you feel the rotation?

To do this I'm given a graph showing gravity reducing non-linearly from 3.7 N/kg at the surface to 0.7 N/kg at 8 x 10^6m. I believe that the equation for a fixed gravitaional pull is E = M x G x H - however with changing gravity as the object rises - how do you calculate this?

Having read many times that there is no theory of quantum gravity, yet physicists at Physics Forums must have some ideas of what a theory of quantum gravity will contain. Is it allowed to discuss these questions at Physics Forums? Wikipedia does allow some current theoretical work to be...

If we are in a cabine in a gravitational field and inside, we have a racket and a ball. We put strings in each side of the racket and we connect the racket to the ceiling of the cabine. This strings only allows us to keep the weight of the racket. Then, we drop a ball to the racket. We do this...

In this experiment, I still can't figure out why the graph between time period and distance from point of oscillation is like that. Why does it first decrease and increase so steeply? I got the second part because it goes near the centre of gravity and time period becomes almost infinite there...

I first find the force of friction to be (2)(9.8)cos(65)(.22), then I find the pull of gravity to be (2)(9.8)sin(65). The full equation I set up to be: 0 = kx + force of friction minus the pull of gravity This gives me the wrong answer, 0.44 . My free-body diagram is that kx and force of...

Hi all. I just watched a great video on gravity wave 'telescopes'. So i have been wondering if any of my intuitive hunches are right about gravity waves. Accelerated masses generate gravity waves that dissipate energy.. So let's say i turn my rocket ship engine on while sitting in deep...

Does the extreme gravity from a black hole cause a blueshift in light approaching the event horizon? sorry for the newb question

Acceleration due to gravity at the Event Horizon of a Black Hole.

I was learning GR and I got to the point where I learned about worldlines and their structure within a Schwarzschild black hole, that space-time itself is curved so that all future worldlines from an event point inward. Since a massive object cannot exert gravity into its past, how does the...

So, this may be a really stupid question, and I strongly feel as though I'm missing something here. How can it be that objects of different masses have the exact same acceleration when mass is in fact resistance to acceleration? And then, if in (a vaccum) I throw upwards M and m ( a bigger and a...

I don't know how to find the center of gravity much less in this problem, so I just created a diagram of the pole with all the forces.

Summary explains it.

In my browsing around various science forums a have come across the comment that the gravity field becomes infinite at the event horizon. I have always thought that this is a misunderstanding, and that it only becomes infinite at the central singularity. Then I found this same statement in...

We are told gravity is a curvature in spacetime but the force of gravity only seems to apply if the body is moving. What moves it if it starts off stationary and then falls?

Summary:: <mentor moved to general discussion> I mean of the discovery of the Graviton or of any other unification theory that would explain gravity and would be compatible with quantum mechanics. And by impact I don't necessarily mean just the understanding of the world - this is implicit -...

Objects fall on Earth at 9.8 m/sec² independent of mass. If gravity is independent of mass why does Jupiter pull an object more than the Earth does? Is that inconsistency within the law or in my perception?

Mass has an effect on the surrounding space which causes two massive objects within the extent of this effect to fall towards each other by crossing the space between them. There is a point source and a direction for the field. The effect of Dark energy causes an expansion of space itself and...

I tried using r * f * sin theta and calculated this: 1.14 m * 9.80 m/s/s * 7.78 kg = 109.7 N*m this was wrong; I needed three significant figures so I did 1.10E2 N*m which was also wrong. Since the torque is due to gravity; would it be -1.10E2 N*m since it’s angle is -270° which is -1?

The apparent ##|\vec{g}|## at the equator, away from Earth's axis of rotation is lower. I know how to calculate this difference of about ##0.03\ \frac{m}{s^2}##. However, I do not intuitively understand this. The closest I've come to an intuitive understanding: An object, whether it is on the...

i have little experience with the differential form of Gauss's Law, and I've tried three times now to arrive at it for a point mass M (spherically symmetric classical gravitational field) but instead of getting an answer proportional to the mass density I keep getting zero. Is the divergence...

On the AG vein, had a thought/question re the work that it is doing, by work I mean joules. So, AG generator is on the ship, as are the occupants. So relative to the AG generator (assume for the time being no one is moving on the ship) the things the generator is acting on are not moving...

v1=460m/s×2, v2=0 m1=m2=5kg R=6378km a1=460m×460m/s/s/6378/km/1000/m×km=0.13m/s/s a2=0 F1=m1×a1=0.66kg×m/s/s F2=m2×a2=0 G=9.81m/s/s F3=(m1+m2)×G=98.1kg×m/s/s (F3-F1)/10/kg = 9.744m/s/s Where the heck did I go wrong?

I'm interested in calculating effective gravity for a point-mass in a spinning gyro or swinging pendulum bob on a rotating planet undergoing any translational velocities and/or accelerations. I want to investigate the theoretical effects of high-energy mechanical oscillation on orbital...

Could the mysterious force of gravity be the force of neutrons being attracted to each other? (There is nothing to suggest this it was a random thought that occurred to me this morning.)

I thing by my logic that gravity must have been at the pre bang stage, but then what did came first gravity or mass?

Since acceleration due to Newton's law decreases as the inverse of distance, it becomes very weak at large distances. Our Sun was unable to pull in matter in the Oort cloud in over 4 billion years. Above about 0.11 light years, using modified Newtonian dynamics equations, gravity decreases by...

Suppose you have a particle, and you measure the gravitational force one meter away in flat spacetime. Add a second identical particle a negligible distance from the first, and measure the force at the same point one meter in flat spacetime away. I expect the force to be very slightly less...

Hi! This is a problem from my physics 1 high school course. I've tried using the first and third equations to determine period (answer of 8326.9544s.), however that was incorrect and I never even touched G. I'm not sure where to go from here at all. Any help is appreciated!

We are given that ##v' = \frac{1}{10}v^2 - g##. I tried using implicit differentiation so that ##v'' = \frac{1}{5}vv' = \frac{1}{5}v(\frac{1}{10}v^2-g)## and set this equal to 0. Hence we have 3 critical points, at ##v= 0##, and ##v = \pm \sqrt{10g}##. Calculating ##v''(0)=-120##, we know the...

In Einstein's theory, gravity is caused by the warping of spacetime. This leads some people to object to gravity being referred to as a force. However, to me it is correct to say that a paperweight resting on a desk is exerting a force on the desk (and vice versa). Is this a correct statement...

Hello, I want to study the trajectory of planets (considered as points) around a body with arbitrary geometry (cube,...). I would like to restrict the simulation to a 2D plane, which would be a plane of symmetry of the 3D object (for example a plane that would cut the cube into two equal...

One obvious difference is that gravity is more general, because there are alternative theories of gravity that differ from general relativity. In this sense general relativity can be thought of as a subset of gravity. But I am interested in a different type of difference. I am interested in a...

Homework Statement: Defining Centroid, Centre of Mass, Centre of Gravity for 2D/3Dshapes Homework Equations: Defining Centroid, Centre of Mass, Centre of Gravity for 2D/3Dshapes Hello all; I am trying to understand the terms:- - Centroid for a 2D shape and 3D shape - Centre of Mass for a 2D...

Can anyone tell me if gravity is greatest for someone standing on the surface of a hollow small sphere or a hollow larger sphere when the spheres are of equivalent mass, and the thickness of the shell is greater on the smaller sphere than the larger sphere (in order to maintain equivalent mass)...

I work in the swimming pool industry. We often lock lumber into concrete by hammering hot galvanized nails half way into the lumber for the concrete to grab a hold of. In an "argument" with my boss, I told him if we set the nails at least an inch below the top of the concrete, the rust will...

For this problem, since the weight force on the "particle" (child) is not always aligned with the tangential circular path of the disks, I couldn't think of a way to use rotational kinematics equations. As such, I tried to solve the problem using work principles (namely, that the change in...

I read everywhere that gravity is slightly stronger at the bottom of a mountain than at the top because the place is closer to the celestial body that causes the "attraction". What I don't understand is that, as you get closer to the center of the planet, there's less matter below you and...

Summary: If a situation can exist where photons can escape black hole gravity, would “dark star” not be a more adequate name? It is commonly accepted that once there is enough material put together to create a sphere with a mass big enough to prevent light from escaping, that this object then...

https://www.sciencealert.com/a-weather-satellite-has-captured-rarely-seen-gravity-waves-in-earth-s-atmosphere This shows satellite images of what are being called gravity waves in clouds. There is an explanation of what happens in the example, using a timelapse 'movie' Is this a nomen...