What is Newtonian: Definition and 336 Discussions

The Newtonian telescope, also called the Newtonian reflector or just the Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton (1642–1727), using a concave primary mirror and a flat diagonal secondary mirror. Newton's first reflecting telescope was completed in 1668 and is the earliest known functional reflecting telescope. The Newtonian telescope's simple design has made it very popular with amateur telescope makers.

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  1. N

    Revisiting the Non-Static Newtonian Limit: Resolving Conceptual Issues

    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...
  2. C

    GR Relation Reduces to Newtonian: Limits Explained

    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...
  3. D

    Newtonian Mechanics - Ball Falling through Syrup

    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]...
  4. bcrowell

    Newtonian force as a covariant or contravariant quantity

    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...
  5. D

    Newtonian Mechanics - Particle in Motion with Air Resistance

    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...
  6. F

    Newtonian vs Einsteinian gravity in everday life?

    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...
  7. A

    Difficulty understanding Newtonian mechanics with stationary force

    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)...
  8. L

    Weak field Newtonian limit

    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...
  9. T

    Eccentricity of projectile in Newtonian gravitational model

    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...
  10. R

    Newtonian particle problem with air resistance

    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...
  11. B

    Total Energy in Newtonian Cosmology

    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 =...
  12. A

    Lagrangian vs Newtonian formalism

    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...
  13. X

    Use Newtonian Model to determine what the scale reads

    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...
  14. J

    Using quantum mechanical forces in Newtonian molecular dynamics

    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...
  15. H

    Calculating Shearing Stress in a Newtonian Fluid

    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...
  16. harrylin

    Newtonian Relativity: Galilean Relativity & Beyond

    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...
  17. H

    Newtonian cosmology vs relativistic cosmology

    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...
  18. M

    Denominator in cosmological constant term in Newtonian gravity

    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...
  19. L

    Using Newtonian field equation to find the gravity inside a sphere

    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...
  20. P

    Newtonian Mechanics:friction, tension and acceleration

    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...
  21. W

    Is Newtonian spacetime flat too?

    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...
  22. U

    Finding the (Newtonian) movement equation of an object in a gravitational field

    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...
  23. A

    What is the difference between Langrangian, Hamiltonian and Newtonian Mechanics?

    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...
  24. B

    Describing quantities independently from frames in Newtonian mechanics

    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)...
  25. C

    When does quantum mechanics turn into Newtonian mechanics?

    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...
  26. L

    Solving Non-Steady Flow of Newtonian Fluid in Circular Pipe

    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...
  27. S

    IB student, Urgently on extended essay(Non Newtonian fluids)

    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...
  28. J

    Newtonian Form of Lens Equation

    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...
  29. R

    Stargazing How to find the Point Spread Function of a Newtonian Telescope?

    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...
  30. A

    Simple Newtonian mechanics problem

    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...
  31. R

    Newtonian derivation of Scwarzchild radius

    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...
  32. SamRoss

    E=mc^2 proof. Why use Newtonian kinetic energy?

    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...
  33. bleist88

    Complete position function of time for multibody systems and gravity (Newtonian)

    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...
  34. P

    Does Anyone Use Newtonian Physics w/ Arbitrary Time Coordinates?

    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...
  35. J

    Solve Newtonian Potential Homework

    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)...
  36. V

    Newtonian limit to schwarschild radial geodesic

    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...
  37. I

    Newtonian Central Force System

    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...
  38. V

    Einsteins Vs Newtonian Solution

    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.
  39. H

    Non Newtonian Fluids: Why & How Do They Respond to Stress?

    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?
  40. D

    AS-level SUVAT / Newtonian physics-based question

    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...
  41. Jonnyb42

    Coordinate Systems: GR vs Newtonian

    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?
  42. J

    Newtonian Gravity involving spheres in a trigonal pyramid

    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...
  43. B

    Newtonian vs Special Relativity: Arguments Against Special Rel

    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?
  44. L

    Verify Newtonian Potential of Thin Spherical Shell

    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...
  45. inflector

    Are Distant Globular Clusters the Key to Testing Newtonian Gravity?

    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...
  46. B

    How can I calculate the force required to compress a spring in a given distance?

    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...
  47. A

    Newtonian Mechanics and Forces Problem

    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...
  48. J

    Newtonian Dynamics: Mowing a Lawn

    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...
  49. Q

    A quick conception question Newtonian physics

    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...
  50. D

    Circular Motion Problem (Using Newtonian Physics)

    Homework Statement The problem is basically a fair ride that has a pole as its base, another pole sticking out of it, the a cable with a chair at the end. I am given the length of the rod sticking out (3.00 m), the cable (5.00 m) and the angle between 30.0\circ. I have to find the time it takes...
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