Newtonian Definition and 337 Threads

So for a point mass in an enclosed shell, the net force of gravity is zero (similar to electricity in a Faraday cage I presume). However, what happens when that point mass is placed in side the ring of mass m and uniform density. Say the outer shell has radius r and inner shell has radius x, so...

Hey all, I was wondering if anyone could help me clear up the following conceptual problem I'm having: When going to the Newtonian limit, authors tend to throw out the terms in the geodesic equation that involve derivatives of the spatial coordinates \frac{d x^i}{d \tau} because they...

In GR for orbits about a central mass in the Schwarzschild metric one can show that \dot r^2 = \frac{E^2}{m^2 c^2} - (1-\frac{r_s}{r})(c^2 + \frac{p_\phi^2}{r^2}). where E=-p_t, r_s is the Schwarzschild radius and 'dot' represent differentiation with respect to proper time. Similarly for...

Homework Statement A steel ball bearing falls through a viscous syrup. The equation of motion is m(dv/dt) = mg - (alpha)v where g = 9.8 m/s^2. The terminal velocity is 0.2 m/s. (a) Determine the value of alpha. (b) Determine the speed at t = 0.04 s. [initial velocity = 0; mass m = 12.6E-3 kg]...

I recently came across a very cool book called Div, Grad, and Curl are Dead by Burke. This is apparently a bit of a cult classic among mathematicians, not to be confused with Div, Grad, Curl, and All That. Burke was killed in a car accident before he could put the book in final, publishable...

Homework Statement A particle of mass m slides down an inclined plane under the influence of gravity. If the motion is resisted by a force f = kmv^2, show that the time required to move a distance d after starting from rest is t = [arccosh(e^(kd))]/√(kgsin(θ) where θ is the angle of...

Let me begin by saying I'm not a student of any kind of physics, I just have a general curiosity about the forces at work in the universe, so for most of the people reading this, my question will probably seem either stupid or strangely obvious! Anyway, my question is this: My understanding...

I apologize if this seems much too "freshman", and may come across as annoyingly simple to some more trained or educated on this board. However I will ask the question anyways as I have failed to find an answer elsewhere. Under Newton's Second Law of Motion, f=ma. thus F = kg (m/s^2)...

Hello, I have to calculate the gravitational field strength g given by the De Sitter-Schwarzschild spacetime. If G=c=1 I get: R_{00}\simeq -kT_{00}+\frac{1}{2}kT\eta_{00}+\Lambda \eta_{00}\simeq -kT_{00}+\frac{1}{2}kT_{00}\eta^{00}\eta_{00} +\Lambda \eta_{00}\simeq...

When we were taught gravitation, we were taught that if a projectile (with mass very less compared to that of the Earth) is projected from the Earth, its path is: 1. Ellipse, if the velocity is less than critical (orbital) velocity. 2. Circle, if the velocity is exactly equal to critical...

Hey guys, first time poster but I'm a physics major and probably going to stick around for a while to help people or get some help myself :P Anyway, on to the problem! Homework Statement A particle is released from rest and falls under the influence of gravity. Find the relationship...

Homework Statement "Consider a perfectly homogeneous and isotropic universe filled with dust of uniform density ρ(t). Let universe expand, dust is carried radially outward from origin. Conservation of total energy E. E = K(t) + U(t) K(t) = (1/2)*mv^2(t) and U(t) = -GMm/r(t) where M =...

I have seen the lagrange equations derived from Newtons laws in the special case, where forces were derivable from a potential. Now with the introduction of hamiltons principle, I think my book wants to say this: We can always find a lagrangian such that the principle of least action holds...

Homework Statement The strings attach to a scale which reads the force. What is the force that the scale will read? Homework Equations F=ma according to Newton's Laws. The Attempt at a Solution Thinking logically, I simply calculated the force of the left side: F=ma...

Hi All, I'm trying to write some "wrapper" software that uses forces calculated from a quantum mechanical potential (ie. Hartree-Fock, DFT, etc.) to evolve a system according to classical Newtonian mechanics (ignoring any periodic boundary conditions, etc.). I believe I have successfully coded...

Homework Statement The velocity distribution for the floe of a Newtonian fluid between 2 wide parallel plates is given by the equation u=3V/2[1-(y/h)^2] where V is the mean velocity. The fluid has a viscosity of 1.915Ns/m^2. When V=0.61m/s and h=5mm, determine: A) the shearing stress acting on...

The following discussion emerged under the topic "at rest" in Einsteinian relativity, and while out of place there it may be worth a little elaboration: Yes indeed. Newton developed a mechanics that uses Galilean relativity as a logical consequence of his model of the world that was based on...

I am working on an introduction to cosmology, I have began by the Newtoniant one (the Hubble law, the Friedmann, fluid and acceleration equations), and some of the aspects of the relativitic one. I want to relate the tow parts by mentioning the shortcomings of the first, and then mentioning the...

In General relativity: an introduction for physicists, the authors derive Newtonian gravity from the EFE, but then they also give a short statement that inserting in the cosmological constant derives down to: \vec{g}=-\nabla\Phi=-\frac{GM}{r^{2}}\hat{\vec{r}}+\frac{\Lambda...

Homework Statement work out g field at a distance r=R/2 from the centre of a spherically symmetric body of radius R. Homework Equations \nabla^{2}\psi=4\pi G \rho \psi=G\int_{V'}\rho\frac{1}{|\vec{r}-\vec{r^{'}}|}d^{3}\vec{r^{'}} -\int_{V}\nabla\cdot g dV = \int_{V}\rho dV...

Homework Statement Alright, the problem is as follows:Three objects are connected on a table. The coefficient of kinetic friction between the block of mass m2 and the table is 0.350.The other two masses are hanging perpendicular to the tabletop, suspended by wires on opposite sides of the...

It is said that minkowksi spacetime is flat. How about galilean (Newtonian) spacetime, is it flat too? If not, what is it? It is also said that it is unknown whether there is geometry or spacetime inside Planck scale. If there is none. I can't imagine how the Planck scale without geometry can...

This is a problem I've been looking to solve for some time. Homework Statement You must find a movement equation for an object in a gravitational field knowing traditional formulas of force and acceleration of gravity (see below).Homework Equations absolute value of the acceleration at a...

What is the main difference between Langrangian, Hamiltonian, and Netwonian Mechanics in physics, and what are the most important uses of them? I'm currently a high school senior, with knowledge in calculus based physics, what would the prerequisites be in order for me to begin Langrangian...

Hello I know that it's possible to reformulate Newtonian mechanics in such a manner that absolute velocities of objects can be defined. By absolute I mean defined without any reference to a specific frame of reference (just as in the article Notes on Mathematical Physics for Mathematicians)...

Since quantum mechanics rules over the microscopic world and Newtonian mechanics rules over the macroscopic world, what is the greatest possible arrangement of atoms to where quantum mechanics still rules and anything more would lead to Newtonian mechanics? In other words where is the line and...

I am to find the velocity distribution where there is non steady flow of a Newtonian fluid in a circular pipe. I did a mass and momentum balance around the system and ended up with the following equation: dp/ds = 4 + 1/e*d/de(e*dp/de) The derivatives in the equation are partial derivatives the...

Hi, guys. I'm doing an extended essay in physics for the IB diploma program. The extended essay is a 4000 word research project on a topic of your choice, and I have opted to do mine in physics. I'm having a lot of trouble narrowing down a suitable research question, and at this point, I have...

Can the Newtonian Form the Lens Equation f=x'x be derived directly from the standard form the lens equation? \frac{1}{f}=\frac{1}{d_{i}}+\frac{d}{d_{o}} x is the distance between the object and the focus on the same side of the object. x' is the distance between the image and the focus on the...

Hi everyone. I am a research undergrad student at the University of Washington and I have been given a conceptual problem to figure out for my astrophysics group... My professor would like us to explain to how how one would find the point spread function of a Newtonian telescope. Here's...

Homework Statement It is the review problem on p.131 of Physics for scientists and engineers ( Serway, 4th edition). It is the classical problem of 2 blocks in an incline(with angle \theta) with masses 2m and m (in order from bottom to the top of the incline) and 1 block suspended trough a...

can anyone say why the derivation works? my teacher went through it in class and sort of said "don't question it" (which i hate) but it's still annoying me now even though it's a few weeks since i finished college. KE = GPE 0.5mv² = GMm/r r=2GM/v² and then if the escape velocity is the...

E=mc^2 proof. Why use Newtonian kinetic energy? In "Does the Inertia of a Body Depend Upon its Energy-Content?" Einstein says that the difference in kinetic energy of a body before and after it releases some energy is... K(0)-K(1)=E(gamma-1) In his previous paper, he worked out the...

Hi, {First off I should share my ultimate goal, which is to have a position function of time of several bodies, let's say in a solar system, so that the position of each body and the acceleration due to gravity on all the other bodies in the system are given at any time t. Although Kepler's...

It's fairly common to use Lagrangian mechanics to handle arbitrary space coordinates. But is it ever actually used to handle arbitrary time coordinates, particularly in Newtonian mechanics? For example, does anyone consider the transformation x = X t = T + uX where (x,t) are normally...

Homework Statement Imagine that you have two particles with masses m and M, interacting with the standard Newtonian potential V=-G*m*M/r . When both masses are positive, you have a textbook example of central force motion. What happens if masses are negative? Discuss the cases 1) m<0, M<0; 2)...

Hello Everyone, While trying to find the Newtonian limit to radial geodesic I was able to find that \frac{d^2r}{d\tau^2}=\frac{GM}{r^2} In the weak field limit we can naively replace \tau by "t" and recover Newtons Law, this though does not sound very rigorous. Can some-one suggest a...

I have a problem and can’t seem to work it out! Ok, here goes: X/|X|^3 = grad U(X) which, when integrated gives U(X)= -1/|X| But I can’t seem to integrate to get the correct answer. Also, if U(X)= -1/(|X|^v ) where v is a constant, then what is grad U(X) now? Thanks for...

hi, I was going through the problem when light is bent by gravity. The Newtonian result is half of result obtained using Einsteins theory. Is this always true for some class of problems. I will be glad if someone can clarify.

Why do non Newtonian fluids such as the cornstarch and water mixture respond to stress the way they do? What prompts the atoms to come together to resist the force?

Homework Statement Diver enters the water at 7.92 [ms][/-1] and comes to rest 1.6m below the surface. Calculate the average total upward force acting on the diver which brings his verticle velocity to zero. From an earlier part of the questions the divers mass is 72kg. Homework...

I just want to ask a simple question: Is it true that Newtonian/Classical Mechanics does not hold true for all coordinate systems, while General Relativity does?

Homework Statement In deep space, three spherical masses are held in fixed positions (by rods light compared to the masses) at three corners of a square of side length sqrt(18) m as shown. The masses of the three spheres are m1 = m3 = 1.76×10^9 kg, and m2 = 2.75×10^9 kg. A relatively small...

I am trying to find any type of argument against special relativity. for example, why would someone think believe that Newtonian relativity is more valid than special relativity?

Consider a thin spherical shell of radius a and mass per unit area \sigma whose centre at O lies a distance r from an external point P. If the gravitational potential r is \Phi(r), verify that the external potential due to the shell will be equal to that due to a point of the same mass as the...

Has anyone here looked at this paper? Testing Newtonian gravity with distant globular clusters: NGC1851 and NGC1904 R. Scarpa, G. Marconi, G. Carraro, R. Falomo, S. Villanova http://arxiv.org/pdf/1008.3526v1 (Submitted on 20 Aug 2010) Globular clusters are useful to test the validity...

Homework Statement There's a question that i tried to solve in a "Newtonian way",but i could only solve it using the concept of energy: supposing that the human bone only tolarates a force of 48.000 N without braking.Calculate the maximum hight H from where a man could jump and the bone...

Problem, Work, and Solution: http://img375.imageshack.us/img375/9987/physicsfinal.png (You can zoom in if needed) Sorry for not using the template, this was done in MS Paint and I didn't want to have to type it all out again... Basically, the problem is to find all tensions (ropes/strings...

Homework Statement A gardener mows a level lawn with an old-fashioned push mower. The handle of the mower makes an angle of 39 degrees with the surface of the lawn. A 111 N force is applied along the handle of the 17.0 kg mower. Neglecting friction, how long does it take for the mower to...

i was having an argument with my friend. He claims that acceleration for object that is lighter, let say a stone (1000kg) and ball (1kg). If we were to throw them up in the sky with the same initial speed, their acceleration would always be 9.81ms^2 (depending on sign conventions). Am i right...