Radius Definition and 1000 Threads

  1. DLeuPel

    Regarding the radius in the orbital velocity

    Would the velocity of a body which is orbiting another body change due to its radius to the center of gravity? If so, why? A body which moves passed a planet and starts orbiting it should have the same velocity it had before ,regarding the fact that it is orbiting a planet. Also, gravity isn’t...
  2. T

    B Brown Dwarf Mass Gain: Does Radius Increase?

    Why wouldn't a brown dwarf grow in radius if it started to gain mass?
  3. prakhargupta3301

    What will be the order of increasing radius?

    My answer is A. Because effective nuclear charge would increase in order Ar<K+<Ca2+ and radius would be inverse of that. However, the answer isn't that. Can you just point me? Also, can you tell me in this question, do we think of the noble gas and the Ca and K ions as single atomic species or...
  4. C

    I Distance between two nucleons

    The potential energy associated to the interaction between nucleons has its minimum (point of equilibrium) at ##r\sim 0.7 fm##, as showed in the following graph: Nevertheless, there are two facts that are, apparently, in contrast with this: - The average distance between nucleons is...
  5. thee qs

    Expression of radius and helical motion in a magnetic field

    Homework Statement charged particule reaches a uniform magnetic B field with a velocity V , and at angle theta with the magnetic field . What is the expression of the relation , expressed as a ratio, of the radius and helical step of the trajectory of the particule . a- 2pi/tan a b- 2pi...
  6. thee qs

    Radius of a particle's path in a B field and magentic momentum force

    ok so 1- the magnetic momentum is = to u in the k axis ( xyz - ijk ) and the magnetic field B = -A/z4 + Be^Cz) , also in the k axis orientation so the magnetic force F , that is applied on the magnetic momentum is given by 4 choices ; and as i can understnd it, 3 of them are...
  7. binbagsss

    GR- effective potential, maximum attainable radius

    Homework Statement part d) from the following question please Homework EquationsThe Attempt at a Solution [/B] sol attached So I see that the idea is that it is a maximum so to set ##\dot{r}=0## and then the maximum value is dependent on some values of J and K, to get the equation. But...
  8. Zubair Ahmad

    I Radius of Gyration: Dist to Axis & Mass Concentration

    For radius of gyration we say distance from axis to a point where would mass is concentrated. isn't that center of mass?
  9. Ajaroy

    What is the internal radius of the optical fibre

    Homework Statement A Capillary tube is made of glass of refractive index n1 . The outer radius of the tube is R.The tube is filled with a liquid of refractive index n2 < n1 .what should be the minimum internal radius of the tube so that any ray that hits the tube would enter the liquid...
  10. L

    B Finding Radius from chord length and tangent distance

    Ok, i have a question. First, i am an engineering student and have done all math requirements up to linear alg. HOWEVER, my geometry is terrible, oh so terrible and i need some spoon feeding right now because i am stuck on a problem. Ok, i saw a really cool tool the other day called a radius...
  11. isukatphysics69

    Radius of convergence of the power series (2x)^n/n

    Homework Statement in title Homework EquationsThe Attempt at a Solution so i know that i have to use the ratio test but i just got completely stuck ((2x)n+1/(n+1)) / ((2x)n) / n ) ((2x)n+1 * n) / ((2x)n) * ( n+1) ) ((2x)n*(n)) / ((2x)1) * (n+1) ) now i take the limit at inf? i am stuck here i...
  12. HappyFlower

    A solid disk of radius 23.4cm and mass 1.45kg....

    Homework Statement A solid disk of radius 23.4 cm and mass 1.45 kg is spinning at 43.1 radians per second. A solid cylinder of radius 12.1 cm and mass 3.33 kg is not spinning. The cylinder is dropped into the center of the spinning disk. After a short time friction has caused both objects to...
  13. hm_tested

    B How to find a length of a "radius" not centered in a circle?

    Generally in a circle, the radius of the circle is uniform around the circle due to it being at the center, this is the obvious part. However, let's say the the radius was shifted away from the center so that it is somewhere in the circle, in this case called r'. Given that the original radius...
  14. S

    MHB On the spectral radius of bounded linear operators

    Hi EVERYBODY: General knowledge: The homogeneous linear Fredholm integral equation $\mu\ \varPsi(x)=\int_{a}^{b} \,k(x,s) \varPsi(s) ds$ (1) has a nontrivial solution if and only if $\mu$ is an eigenvalue of the integral operator $K$. By multiplying (1) by $k(x,s)$ and...
  15. Poetria

    Addition of power series and radius of convergence

    Homework Statement ##f(x)=\sum_{n=0}^\infty x^n## ##g(x)=\sum_{n=253}^\infty x^n## The radius of convergence of both is 1. ## \lim_{N \rightarrow +\infty} \sum_{n=0}^N x^n - \sum_{n=253}^N x^n## 2. The attempt at a solution I got: ## \frac {x^{253}} {x-1}+\frac 1 {1-x}## for ##|x| \lt 1##...
  16. E

    Finding the change in weight from the force & difference in height (y)

    Information Given:In 1956, Frank Lloyd Wright proposed the construction of a mile-high building in Chicago. Suppose the building had been constructed. Question: Ignoring Earth's rotation, find the change in your weight if you were to ride an elevator from the street level, where you weigh 708...
  17. E

    Finding the Kinetic Energy using the mass, radius and initial KE

    Information Given:Zero, a hypothetical planet, has a mass of 4.2 x 1023 kg, a radius of 2.8 x 106 m, and no atmosphere. A 10 kg space probe is to be launched vertically from its surface. Question: (a) If the probe is launched with an initial kinetic energy of 5.0 x 107 J, what will be its...
  18. isukatphysics69

    Find the radius of the circle for this airplane

    Homework Statement Homework Equations f=ma v^2/r The Attempt at a Solution Σfx = FNcos(θ) = (v^2/r)*m Σfy = FNsin(θ) - mg = 0 FN = mg/sin(θ) (mg/sin(θ))*cos(θ) = (v^2/r)*m gcos(θ)*r = v^2*sin(θ) r = v^2sin(θ)/gcos(θ) v = 150m/s θ = 38 r = 1793m i have...
  19. Tannerbobanner

    How does radius affect frequency in uniform circular motion?

    I am writing a lab report on the effect of the radius of a string on the frequency of rotation on an object in horizontal uniform circular motion. My hypothesis is: If the radius of the string from the origin of rotation increases, then the frequency will decrease because frequency has an...
  20. M

    I Relationship between star radius and luminosity

    In a PDF presentation on star formation that I'm currently reading, I ran into the following statement: "If we observe an increase in a star's temperature but without any changes in its luminosity, it means the star is shrinking (its radius is decreasing)" I'm having trouble understanding...
  21. K

    Find the force as a function of radius to pull a ribbon

    Homework Statement A disc is free to rotate about an axis passing through its center and perpendicular to its plane. The moment of inertia of the disc about its center is I. A light ribbon is tightly wrapped over it in multiple layers. The end of the ribbon is pulled out at a constant velocity...
  22. rpthomps

    I Noble Gases vs. Halogens: Which Has a Greater Atomic Radius?

    Does the noble gases have an atomic radius decrease or increase from halogens?
  23. Specter

    Finding the radius of the satellite's circular orbit

    Homework Statement My title was supposed to say "Finding the radius of the satellites circular orbit" but I can't seem to edit it. << Mentor Note -- Title fixed for you >> A 500 kg satellite experiences a gravitational force of 3000 N, while moving in a circular orbit around the earth. a)...
  24. Cianturyo

    How to calculate changes in the radius of a surface under compression?

    How do i calculate percentage of changes in radius, when the surface which cause the radius, will be compressed by a certain percentage? To illustrate better, i have drawn the picture of the question. How to calculate radius ?? if radius A Is known. Changes in the surface is also known. Thank...
  25. Jianphys17

    Question on classical electron radius

    Hi at everyone, why on wiki there is written: " According to modern understanding, the electron is a point particle with a point charge and no spatial extent. Attempts to model the electron as a non-point particle are considered ill-conceived and counter-pedagogic " I don't understand this...
  26. jonnybmac

    Linking gravity, angular velocity and radius

    Homework Statement I am having trouble linking gravity to the radius of the Earth and angular velocity. I was using this as a solid method to confirm the equation for values of a different sort based on centripetal acceleration. When inputting the values though it does not add up and I cannot...
  27. K

    Finding the radius of the sphere

    Homework Statement In a spherical bowl a small ball is jumping around. The ball hits the bowl in two spots and moves in two different trajectories in times T1, T2. Find the radius of the bowl. Homework Equations Newton's laws of dynamics. The Attempt at a Solution The only thing I could...
  28. S

    MHB AO+BO+CO≥6r where r is the radius of the inscribed circle

    From the entrance examinations to Ghana University ,from high school, i got the following problem: If O is the center of the inscribed circle in an ABC trigon,then prove that: AO+BO+CO\geq 6r where r is the radius of the inscribed circle.
  29. zonde

    I Coordinate singularity at Schwarzschild radius

    I would like to ask how rigorous is the statement that Schwarzschild metric has coordinate singularity at Schwarzschild radius. The argument is that singularity at Schwarzschild radius appears because of bad choice of coordinates and can be removed by different choice of coordinates. However...
  30. Bobs

    I'm getting two different answers for the atomic radius of iridium

    I'm getting too different answers for atomic radius of iridium. I've already found 1.34 x 10-8 but all shows different answers. I mean like 1.34, 1.35, 1.36... Are those correct?
  31. S

    Ratio Test and Radius of Convergence for ∑ ((n-2)2)/n2, n=1: Homework Solution

    Homework Statement ∞ ∑ = ((n-2)2)/n2 n=1 Homework Equations The ratio test/interval of convergence The Attempt at a Solution **NOTE this is a bonus homework and I've only had internet tutorials regarding the ratio test/interval of convergence so bear with me) lim ((n-1)n+1)/(n+1)n+1 *...
  32. Pedgepoke

    Vertical Circles Centripetal Acceleration

    Homework Statement A jet pilot takes his aircraft in a vertical loop. V is 840 km/hr (233.3 m/s) find the min. radius of the loop to that the centripetal acceleration at the bottom does not exceed 6 Gs. Homework Equations a = v^2 / r F = ma The Attempt at a Solution I don't know where to...
  33. J

    Constant acceleration and radius of curvature

    Homework Statement Homework Equations The Attempt at a Solution The normal acceleration of the particle at any instant is given by an = v2/r . v is the speed at any time and r is the radius of curvature . Minimum radius will occur when ratio v2/an is minimum . I think this will occur when...
  34. eigenmax

    I How does one find interaction radius for Coulomb barrier?

    For a proton striking an atomic nucleus (in a Cockcroft-Walton accelerator, for example), the Coulomb barrier must be overcome. The calculation of the Coulomb barrier is U = k Z1Z2 e2 / r r is interaction radius. How can I find that? For a proton to enter the atomic nucleus what would it be?
  35. M

    MHB What is the Center and Radius of a Circle?

    A. Determine the center and radius of circle. B. Also, find the y-coordinates of the points (if any) where the circle intersects the y-axis.
  36. S

    Radius and centripetal relation

    Homework Statement the file given Homework Equations F=mv^2/r The Attempt at a Solution I do not understand why the centripetal force is 2a and not 2/a since the radius of X is twice longer. When I use the equation above, raidius is inversely proportional to the acceleration. Is radius...
  37. K

    Finding velocity given radius and acceleration

    Homework Statement A car travels over a hump in the road of radius 20 meters. How fast is the car traveling if the occupants feel a net acceleration of 3.8 m/s2 Homework Equations a = v2/r v = √ar The Attempt at a Solution I did this but according to my teacher this isn't correct. v = √(3.8...
  38. S

    Slope of Force vs Frequency^2 and Radius vs Period^2 Graphs

    Homework Statement An experiment that involved swinging a mass in a circle was conducted. After graphing both sets of data, I obtained linear graphs of which I calculated the slopes for. I got a slope of 3.5 for the force vs frequency^2 graph and a slope of 0.73 for the radius vs period^2...
  39. Y

    Fire Hose Power Output, Given Height and Radius of Hose

    Homework Statement A fire hose for use in urban areas must be able to shoot a stream of water to a maximum height of 34 m. The water leaves the hose at ground level in a circular stream 4.0 cm in diameter. What minimum power is required to create such a stream of water? Every cubic meter of...
  40. A

    What Are the Correct Units for Kepler's Third Law?

    I am confused about the units used in Kepler's 3rd law. Is T supposed to be in years or days? Is R supposed to be in kilometers or meters? Is there ever an instance where one combination of units is preferable over another (for example, if you want to use the answers from Kepler's third law to...
  41. A

    Uniform Circular Motion - distance

    Homework Statement An object with mass m = 2 kg is moving in a uniform circular motion with radius r = 2m as shown in the figure. It takes π seconds for the object to travel from θ =0 to θ = 180 degrees. What is the distance traveled by the object in 20 s...
  42. HRubss

    Radius of largest possible loop of an Airplane.

    Homework Statement A 2250 kg airplane makes a loop the loop (vertical circle) at a speed of 320 km/hour. Find (a) the radius of the largest circular loop possible and (b) The force on the plane at the bottom of this loop. Homework Equations F = m*a Centripetal Force = m * (v2)/r "Critical...
  43. N

    Cyclotron Radius of Proton: .625m

    Homework Statement The cyclotron radius of a proton moving at 3.0*10^5 m/s perpendicular to a 5*10^-6T magnetic filed is: Homework Equations r=mv/qB The Attempt at a Solution So plug and chug: r= (1.6*10^-27)(3*10^5)/(1.602*10^19)(5*10^-6) r=625.5m However they have it down as .625m. Where...
  44. W

    Solving for Radius in Magnetic Field: q of Sr+?

    Homework Statement The Lorentz Force can be used to sort ions (atomic or molecular) based on their charge to mass ratio. This configuration has been used to separate isotopes and as a mass spectrometer. A beam of Strontium ions Sr+ is accelerated through a potential of 500 V and injected into...
  45. P

    Radius of a planet with the same density as Neptune

    Homework Statement "In January 2006, astronomers reported the discovery of a planet comparable in size to the Earth orbiting another star and having a mass of about 5.5 times the Earth's mass (5.97 x 10^24 kg). It is believed to consist of a mixture of rock and ice, similar to Neptune. If this...
  46. M

    B Surface volume of 3-sphere with radius of 2 Planck length?

    What is the surface area ("surface volume") of a 3-sphere having a radius of 2 Planck lengths? Is the product of the Planck's constant, Einstein's proportionality constant and Planck time also equal to this volume? Does this equivalence signify anything? What does it signify?
  47. M

    MHB Equation and Point Check for Circle of Radius 1

    A. Write the equation of radius 1 centered at (0,0). x^2 + y^2 = 1 B. Does the point (3/5, 4/5) lie on the circle? (3/5)^2 + (4/5)^2 = 1 (9/25) + (16/25) = 1 25/25 = 1 1 = 1 Yes, the point (3/5, 4/5) lies on the circle. Correct?
  48. T

    I What happens at r ≤ rS in the Schwarzschild metric?

    If the Schwarzschild metric is, by construction, valid for ##r > r_S##, where ##r_S## is the Schwarzschild radius, so it does not make sense to talk about what happens at ##r \leq r_S##, because there will be no vacuum anymore. What am I getting wrong?
  49. lfdahl

    MHB Prove that the radius of the incircle of △ is rational

    Let $\bigtriangleup$ be an isosceles triangle for which the length of a side and the length of the base are rational. Prove that the radius of the incircle of $\bigtriangleup $ is rational if and only if the two right triangles formed by the altitude to the base are similar to a right triangle...
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