Newtonian Definition and 337 Threads

What types of objects does Newtonian mechanics deal with? Is it just rigid bodies? I’m not sure how Newton’s laws could explain something like the motion of a wiggling rope.

I'm looking for a source of harder mechanics problems, preferably with solutions. I'm supposed to use the Young and Freedman book, but I find it rather teadious and superficial; most problems don't match the difficulty and depth of the ones on the exam. I had my mid-term tests recently, and got...

Recent discussions on pressure as a source of gravity and the related Tolman paradox have reminded me that few people seem to be aware that even in Newtonian gravity the pressure is related to the potential energy, which I've mentioned a few times on these forums before. This is easy to show...

Hello! I am reading A first course in General Relativity by Schutz and at a point he proves that for a weak gravitational field and assuming ##\Lambda = 0## we have ##\Box \bar{h}^{\mu \nu} = -16\pi T^{\mu \nu}##. Leaving the notations aside, he says that for a weak gravitational field (and...

Homework Statement Given an plate that has 2 pins attached to it. Each pin has a single balanced circular disc firmly attached to it. Each pin can rotate on their axis in both clockwise and anti clockwise direction. (See image below) Now, assume the discs are rotating with the same angular...

I have a (somewhat) strange energy equation which has the following form: KE = A + B W + C \exp(-D W), where A,B,D are known constant, C is an unknown constant to be determined and kinetic and potential energy are given by KE and W respectively with W\equiv W(r) i.e. is a function of...

Greetings to all stargazers! I am a happy owner of a Newtonian telescope 200/1200 on Dobson mount, more detailed specifications on this link (http://skywatcher.com/product/dob-8-traditional/). It has a 2” focuser with a 1.25” adapter. So far, I was using only the two included eyepieces, 1.25”...

Suppose you wanted a thought experiment about a variation on the vacuum (i.e., the spatial slice of spacetime) in which the quantum effects were absent or negligible, and the vacuum energy was zero . What would you call it? You can't call it the vacuum, because this Newtonian version of the...

http://www.pitt.edu/~jdnorton/Goodies/Dome/ I think that most wonderful point in this story is that the person who writes such texts is Distinguished Professor of University of Pittsburgh. Nevertheless I believe that the question he stated up can confuse an undergraduate student and thus...

In his little book for the layman, Seven Brief Lessons on Physics author Carlo Rovelli states: What is it about SR which is incompatible with gravity-as-a-force?

Homework Statement ρ= density, vi = i-th velocity component, gi=i-th component of gravity vector, p=pressure, μ= viscosity, D/Dt = material derivative Homework Equations Continuity equation: div v = 0 The Attempt at a Solution

Homework Statement Consider a point mass of mass m suspended from an ideal, massless spring. Let ##\theta ## be measured from the vertical. Find the displacement of the mass as a function of time if the spring is initially stretched/compressed a distance ## l_0 ## and has an initial velocity...

Homework Statement A block of mass 100 grammes was stationary on the flat surface at ##x = 0##. At time ##t = 0## a horizontal force of 10 Newtons was applied on the block in the positive x direction during ##\Delta t = 3## seconds. Find at what x position the block will stop, if the...

Homework Statement A comet moves around a stat in ##xy## plane along elliptical orbit, described by $$ 0.16 x^2 + y^2 = 4 $$ where ##x, y## are in ##AU## 1) Sketch the comet in the ##x,y## coordinate system denoting all orbit parameters 2) Find the semi major and minor axes of the orbit...

Hi folks, Tell me please why in classical Newtonian physics one can say that the space and time are independent? But we have equations of motion which clearly show this dependence (x=Vt; x=x0+1/2at^2+v0t). Thank you.

Homework Statement The space shuttle is in a 300 km-high circular orbit. It needs to reach a 520 km - high circular orbit to catch the Hubble Space Telescope for repairs. The shuttle's mass is 6.5 E4 kg. Mass of the Earth = 5.98 E24 kg. Radius of Earth = 6.37 E6 m. How much energy is required...

I recently put together a simple 2D gravity simulator and I'd like to get some feedback or suggestions you may have for future updates. I'm planning to make a 3D version and improve the animation (framerate, realism, etc). This first simulation includes the Sun, Mercury, Venus, Earth, and Mars...

Homework Statement I'm trying to plot Newtonian orbits in Mathematica with the goal of extending this to orbits including GR after. I've derived equations for r(t) and ##\phi##(t) (see below) by integrating ##\dot{r}## and ## \dot{\phi} ## (see below also) from E = 1/2mv2 +V(r) with velocity...

A prisoner in jail decides to escape by sliding to freedom down a rope provided by an accomplice. He attaches the top end of the rope to a hook outside his window; the bottom end of the rope hangs clear of the ground. The rope has a mass of 10 kg, and the prisoner has a mass of 70 kg. The...

I understand that General Relativity can make a difference between a spinning and non spinning mass thus can make better prediction for planetary orbits for example. The effect is frame dragging. However if we simulate a Newtonian gravitation and instead of representing a planet as a sphere...

In Schutz says When we have weak gravitaional fields then the line element *ds* is $$ ds^{2}=-(1+2\phi)dt^{2}+(1-2\phi)(dx^{2}+dy^{2}+dz^{2}) $$ so the metric is $$ {g_{\alpha\beta}} =\eta_{\alpha\beta}+h_{\alpha\beta}= \left( \begin{array}{cccc} -(1+2\phi) & 0 & 0 & 0\\ 0 & (1-2\phi) & 0 &...

So I was reading that the equivalence principle of Newton doesn't work because of a thought experiment. They said that an experimenter shoots bullets( 1 per second) from the bottom of the elevator to the top. This happens in outerspace where the elevator moves up with accleration g. And this...

Hello, I wanted to know how Einstein's General Relativity and its equations simplify to Newton's Universal Law. Einstein's equation is obviously a much more generalized version of Newton's law and gives much more accurate predictions that Newton's laws even if we don't think of Newton's gravity...

In the Newtonian theory of cosmological perturbations, a density excess ##\delta\rho## in a localised region of spacetime leads to the equation of motion ##\ddot{\delta\rho} \sim G\delta\rho##. I can see that this follows directly from Newton's gravitational law. Why does this equation lead to...

I am studying an inviscid fluid. I am trying to characterise the fluid. Does it make sense to call it Newtonian or should I avoid this designation? What I mean is - if there are no viscous stresses then does it make sense to characterise it's response to viscous stresses? (That box that doesn't...

When does GR apply in gravitational fields as opposed to Newtonian gravitation? Another words, what would be the strength of the graviatational field before we abandon Newtonian gravity and start implementing GR? 10 g's, 20 g's?

Hi. I read that the Lorentz invariance Minkowski norm of the four-momentum $$E^2-c^2\cdot \mathbf{p}^2=m^2\cdot c^4$$ has no analogue in Newtonian physics. But what about $$E-\frac{\mathbf{p}^2}{2m}=0\quad ?$$ It might look trivial by the definition of kinetic energy, but it's still a relation...

Homework Statement Figure 5-12 shows a block S (the sliding block) with mass M 3.3 kg. The block is free to move along a horizontal frictionless surface and connected, by a cord that wraps over a frictionless pulley, to a second block H (the hanging block), with mass m 2.1 kg. The cord and...

Hello All, I have a question for which I'd like an authoritative answer, if some physics genius would be so kind. I'll try to provide as much background as I can but follow up questions for clarity are more than welcome! So I'm working on the design for a patent application and it involves a...

Homework Statement Homework Equations $$\frac{\omega}{v}=\frac{s}{r}$$ The Attempt at a Solution How to get the equation above? Cause $$\frac{s}{r}=\omega$$ & $$\frac{\omega}{v}=\frac{1}{r}$$ since v=rw. Source: http://www.relativitycalculator.com/Newton_Universal_Gravity_Law.shtml

For an equations such as this what goes into the θ? θ = sinθ or θ = θ? Let's say if the angle of displacement = 45° do I just plug 45° as θ into the equation below or should it be sin(45°)? Or is it θ = S/R ? ωf2 = ωi2 + 2 α (θf - θi)

Homework Statement truck moves at 22,5 m/s On board the truck, behind, is a box. the static friction coefficient for the box, is 0,250 with regard to the friction between truck floor and the box floor. calculate the shortest possible stopping distance, such that the box does not slide at...

Sorry for the amateurish setup that follows. Here's my thought experiment. Consider a 2-dimensional universe on the Cartesian plane. Earth is located at point (0,0). There is a binary system {A,B} oscillating around (1,1). To simplify, assume that the oscillation is 1-dimensional and occurs on...

I am wondering if things can be objective but not universal.

Homework Statement Word problem. Fisherman lifts a trout with his fishing rod directly upwards. The fish is a trout. The trout's mass is 0,45Kg. The trout's acceleration is 2,5m/s^2. a) draw free body diagram for the trout b) with how great a force, does the fishing line affect the trout...

Homework Statement The blocks of mass 20.0 kg and 10.0 kg are initially at rest on the floor and are connected by a massless string passing over a massless and frictionless pulley. An upward force F is applied to the pulley. Find the accelerations a_A of block A and a_B for block B when F is...

If I am asked to show that the tt-component of the Einstein equation for the static metric ##ds^2 = (1-2\phi(r)) dt^2 - (1+2\phi(r)) dr^2 - r^2(d\theta^2 + sin^2(\theta) d\phi^2)##, where ##|\phi(r)| \ll1## reduces to the Newton's equation, what exactly am I supposed to prove?

1. The problem statement, all variables and given/known You are playing with your daugther in the snow. She sits on a sled and asks you to slide her across a flat , horizontal field. You have a choice of (a) pushing her from behind by applying a force downward on her shoulders at 30 degrees...

It is said many times, from the days of Einstein, Minkowski and Poincaré, that Classic or Newtonian Mechanics are not consistent with motion at relativistic speeds, that a new relativistic mechanics is needed, viz. Albert Einstein: … the apparent incompatibility of the law of propagation of...

Homework Statement Hello, Regarding the idea of Newtonian force pairs, imagine a bottle resting on a table: Weight force exerted on bottle by Earth and normal contact force on bottle by table are not Newtonian force pairs because they are different types and act on the same object. Weight force...

These buckets are being suspended. The cords have no mass and each bucket is 3.5 kg. a.) Find the tension in the upper cord (T1) and the lower cord (T2) b.) If the apparatus is pulled upwards from the top of the upper cord, what are the new tensions of each cord? I understand the...

First. Do you consider Copenhagen Interpretation as leftover of Newtonian days when things are classical? Because in Copenhagen you have to divide with a classical and quantum cut that modern Decoherence tries to overthrow. . Second. And this is about the thread "Quantum mechanics is not...

I asked recently on another thread about relativity and its affect on gravitation. I have been informed that gravity is due to how energy bends spacetime, not the Newtonian idea of mass or even the special "relativistic mass." However this leaves me wondering why general relativity does not...

Hi. I've only ever seen Noether's theorem formulated ond proven in the framework of Lagrangian mechanics. Is it possible to do the same in Newtonian mechanics, essentially only using F=dp/dt ? The "symmetries" in the usual formulation of the theorem are symmetries of the action with respect to...

When compressible effects are accounted for, viscosity should vary with temperature. Doesn't this violate the concept of Newtonian fluids, where shear stress is linearly proportional to the strain rate?

Hello, So i know that the gravitational acceleration experienced by a body is -GM/||d||^2 * dhat, where dhat is the current displacement unit vector, which has a magnitude of 1. the magnitude of a vector is equal to to the square root of the sum of its squared components. This will be a 2d...

Could be a book, research paper or website, the focus is on the contradiction and compatibility of the two (?) bodies of physics.

Lagrangian in classical mechanics equals L=T-V, where T is kinetic energy and V is potencial energy. But, how to compose such a Lagrangian? Everywhere, where I found, it is only assumed and then equation ##d/dt (\partial L/\partial \dot{x})-(\partial L/\partial x)=0## is used. But, why L=T-V, is...

Homework Statement A canon is burried on a hillside, so the barrel is exactly at the height of the surface. The hillside creates angle theta with vertical, where 0 degrees < theta < 90 degrees. A canonball is fired with speed v_0 perpendicular on the hillside. The angle between velocity_0 and...

OK. I'm sure this is probably been considered before but it is my musings coming off a recent attempt to photograph the Andromeda Galaxy. I did a few two minutes or so shots of Andromeda and stacked them for a total of about 14 minutes. Fairly nice. There is some structure to be seen but...