Gravity Definition and 1000 Threads

In a physics test in a Norwegian website of a school book, it says following: True or false? (1) According to Newton's 3rd Law, the weight of a book that is on a table is just as big, but opposite the force on the book from the table (normal force). FALSE. (2) According to Newton's 1st Law...

Hi, I teach a physics class to a group of homeschooled students. Many of them aren't yet at the level of algebra. Last week we went over Newton's laws and did some experiments to show objects fall at the same rate regardless of mass. One student though, has asked me to explain why the mass...

The reason I made an account is to ask about the effect of gravity from an extra planet hiding behnd the sun. I think that if this was the case we would see much great impacts¿ say like the tides. Would they not be extremely high and low? Nonstop quakes that would be felt across the world? I...

1. The Clock Hypothesis states that the rate of a clock does not depend on its acceleration but only on its instantaneous velocity. This has been experimentally verified at very high accelerations. 2. A clock in a gravitational field experiences time dilation and runs slower that one not in a...

Why there must be a way of including gravity into a quantum theory? What leads scientists to believe that ultimately all the interactions must be subjected to quantisation? Would that be because we describe all other interactions in quantum theory and so we must include gravity on this...

latest paper Ghirardi-Rimini-Weber model with massive flashes Antoine Tilloy (Submitted on 12 Sep 2017) We introduce a modification of the Ghirardi-Rimini-Weber (GRW) model in which the flashes (or collapse space-time events) source a classical gravitational field. The resulting semi-classical...

Homework Statement Two balls are given, the distance between their centers is 8R. Both have a radius of R.[/B] One ball has a mass of 2m and the other has a mass of m. The question is: What will be their velocities right before they touch each other Answer: Vm=√(GM/R), V2m=0.5√(GM/R) Homework...

https://en.wikipedia.org/wiki/LIGO#/media/File:Simplified_diagram_of_an_Advanced_LIGO_detector.png The axis on the bottom of the graph depicts frequencies between 20-1000 Hz which are sound waves. Again, how can a sound wave (gravity waves) propagate in the near vacuum of stellar space...

Testing Quantum Gravity Johan Hansson, Stephane Francois (Submitted on 19 Oct 2017) The search for a theory of quantum gravity is the most fundamental problem in all of theoretical physics, but there are as yet no experimental results at all to guide this endeavor. What seems to be needed is a...

GW170817 showed that gamma rays came 2 seconds after gravitational waves. (after 130M years) Are these two seconds uncertainty at determination of difference of these speeds? Or is it possible to explain, why 2 seconds of difference, or is it possible to explain, at least, a part of this...

Homework Statement [/B] Hi everyone! So I've got this similar problem as I posted yesterday, but this one is slightly different due to the presence of gravity: A particle in gravitational field ##~~g## starts traveling upward (positive direction) along the y-axis from ##~~y=0## with the...

Homework Statement We were given this question on a worksheet last lecture. The question is this: ‘Throw a tennis ball/your pen/some non-dangerous object into the air, straight up (and catch it again), observe its motion. Use your observation to measure the gravitational acceleration due to...

If I compress a spring beyond its most relaxed point it will have more energy and thus by General Relativity produce a stronger gravitational field than the uncompressed spring will. But suppose instead I pull in the opposite direction and stretch the spring beyond its most relaxed point it is...

Hi everyone, today, I have a question about quantum gravity, good to begin with. I used Newton's formula to calculate gravity for nêutron , the result exceeded Planck's radius, the question is: could it be that gravity is not necessarily connected to the mass of a particle, nor with graviton...

Hello Please why the mass m3 does not fall?

Did the 2017 eclipse prove Einstein was right or the jury is still out? I can't find any references to the new measurements and what they proved (or did not).

I thought of another question(s) :) does temperature affect the rate of the decay at all? Does temperature effect the energy of the decay; in that the energy of the electron anti neutrino would be higher?

Can I mimic gravity with Magnetism or angular momentum?

If the inverse square law for gravity varies with distance or distribution of matter, might the need for “dark matter” be obviated?

Hi all I read a question on this subject from some time ago but was not satisfied with the clarity of the answer and in the light of recent experimental results I wish to clarify my understanding of this ancient scientific question. What is the cause of Inertia? So is inertia simply the total...

If I keep iron fillings on a cardboard with a wire carrying current in some direction, I know that the fillings will orient in concentric circles.But what happens if I keep the fillings on the underside of the cardboard? Is it possible to make them hang in the air against gravity with a...

In quantum gravity, I get 'mixed signals' as regards renormalizability. My state of confusion is being caused, I suspect, by an incomplete understanding of what is covered under t'Hooft's 1972 proof that non-Abelian gauge theories are renormalizable. ( = Nobel Prize 1999). Specifically, some...

So my first question is :- Is there any quantum theory success to derive the principle of general relativity? and If this happen, Does this mean we succeeded in finding a quantum theory of gravity?. and My second question is :- Is quantized background-independet theories exists? and If so, is...

(context) I can remember reading about an atomic clock that could show time running slightly differently rates at different heights, due to the differences in gravitation. Is it realistic to think of it the other way round, ie gravity as an effect of miniscule time rate difference ? If an...

Hi Guys, So I am using the following simulation for this activity (Mass and Springs). The concept I need help with is to understand why when attaching a mass, the spring moves downward when the gravity is zero? If there is no gravity my limited understanding is that spring should not move...

Hi, Please could someone kindly explain how zero weightlessness is achieved in this aircraft. I have tried to use my own understanding and what I have read online. My ideas are: To experience weightlessness the plane must be in freefall so the only force acting on it must be gravity. Since...

In simple examples of throwing a ball upward and observing it's arc, the calculations include a constant vector acting downward on the ball throughout it's flight. Without getting into the complications of that vector changing magnitude with altitude, it does not change with respect to the speed...

Homework Statement -Two objects of negligable radius and masses M and m are fixed in space at the distance R. Gravity is the only force acting between those two bodies. At some point in time, body of mass m is realized and starts moving due to gravity toward statical mass M. Find v(x) and...

So, I'm going to learn general relativity but I'm confused in which book I start with Bernard Schutz book seems excellent but I'm more interested in d'Inverno book, And Misner/Throne Book Seems complete but its giant and good for reference, So I think I will go with d'Inverno , but first I need...

Homework Statement I have two objects that slide without friction on a circle of radius R, oriented in a vertical plane, as seen on the attached photo. The heavier object (mass = 3m) is attached to a spring with an unstretched length of zero and spring constant k. The fixed end of the spring...

That is to say, how does time behave in a region of space where multiple gravitational fields cancel out their accelerating effects? I understand that time "slows down" in a gravitational field, but does this depend on the actual presence of the field, or instead the actual net acceleration...

Feel free to correct anything I state here. I'm trying my best to understand some rather complex (for me) ideas about time dilation. So if I understand correctly, increasing velocity compresses time, causing you to exist more slowly relative to anyone not moving at that velocity. Similarly, the...

In his recent letter to the physics community, Susskind says Gravity and Quantum Mechanics is inseparable. Read it here . Frankly, I do not fully understand his letter or the claim that he is making. What do you think?

the news are reporting this paper Ghirardi-Rimini-Weber model with massive flashes Antoine Tilloy (Submitted on 12 Sep 2017) We introduce a modification of the Ghirardi-Rimini-Weber (GRW) model in which the flashes (or collapse space-time events) source a classical gravitational field. The...

I want to demonstrate to flat earthers that water does indeed stick to a ball. If we want to do a scale model of the earth, at which radius will gravity overcome the surface tension?

Is gravity an attractive force of matter, or is it a universal force of expansion and pressure that exists in apparently empty space? Does matter attract objects near it, or does matter merely block gravity pressure on on any given side of a material body, giving the illusion that the matter...

Now, I know that it is theoretically possible for negative mass to exist and for negative energy to exist. But any gravity would act on all objects and all energy, no matter if that mass and energy is positive or negative. So negative gravity would for example, pull a person upwards. Now yes, I...

Hey guys, I'm itching to find out what you know or theories about gravity and light... My first question that I pose to you is this.. If the cosmic speed limit is set by light.. then why can gravity affect it? Consider this. Light is traveling away from a black hole.. gravity is so...

I have read on the internet that if an object rests on a table, that object will exert the force of its weight on the table. But, for some reason, that doesn't make sense to me. If I have a 10 kg book that rests on a table, the gravitational force on that object will be 98 N. If gravity is...

Is there any experimental proof which shows that the force of gravity works at Planck length? Has it been verified already? Is it verifiable?

If I drive a plane and the force of engine is bigger than force of gravity of it , if the engine is turn on always ,and assuming no air , will the plane continue moving up and escape from the gravity ?

I would have thought that this would have been tested before but this paper suggests that it is a new theory. arXiv:1709.02481 [pdf, other] A possible explanation for dark matter and dark energy consistent with the Standard Model of particle physics and General Relativity A. Deur Comments: 6...

I'd like to ask about a hypothetical situation. A human, wearing a jetpack, for example, accelerates forward with 200,000 m/s^2 and therefore, experiencing extreme g-force of roughly 20,408 g. If there will be a hypothetical device that will be able to redirect the gravity force (g) to elswhere...

Physicists had success in developing a relativistic quantum mechanics, also Quantum Field theory. I wonder why it's not the same with a quantum gravity theory. I suppose this is mainly because we do not have good emphirical information from a place where Einstein's theory fails: black holes...

Preface There are lots of times in physics when we use approximations of a more accurate or fundamental physics theory because it is easier to work with. For example, in quantum chromodynamics (QCD) lots of calculations are done using the Schwinger-Dyson equations rather than the actual...

Homework Statement 1. Homework Statement The Earth turns once around its axis in 24.0 hours. We will assume that it is perfectly spherical, with radius 6400 km. The mass of the Earth is taken to be 6.00 × 1024 kg. The gravitational acceleration on the surface is taken to be g = 9.80 m/s2 . a)...

Using special relativistic calculation it can be showed that magnetism is a result of electric charges in motion. using the same argument, why can't we find a magnetic force like thing for gravity?

Can someone comment on https://arxiv.org/abs/1705.00626 ? It looks quite technical, but potentially very important.

Please see the below image, it is a closed and well sealed circulated pipe structure, fully filled with water and no air inside. The density of that green object is greater than water (say 1.2 while water is 1). In this situation, will the green object be sunk? Better with some explanations...

I've seen a little bit about the gravity light. I think it works in a simple way, a weight at a certain height has gravitational potential energy depending on how far the weight will fall, this quantity represents the total energy we have at our disposal to power a light. Now we normally think...