Radius Definition and 1000 Threads

  1. M

    Electron Radius in a Bending Magnet

    Problem: 15 MeV electrons enter a bending magnet with a magnetic field of .7 tesla. What is the radius of the path of electrons? Equation: r = mV/Bq B = .7 tesla q = 1.6 x 10^-19 C My problem here is that I don't know how to find the velocity of the electron for this...
  2. E

    Determining angular velocity radius and velocity of the center of rotation

    Hey, I am trying to solve the following problem: va=vr+ ω × rra vb=vr+ ω ×(rra+rab) vc=vr+ ω × (rra+rac) I know the vectors va, vb, vc, rab and rac and I want to know the angular velocity vector, the radius rra and the velocity vr. Physically it means that I know 3 points on a rigid...
  3. D

    Radius of Circular Track: Solve for 745m & 475°

    Homework Statement A car travels a distance of 745 m along a circular track, and the driver finds that she has traveled through an angle of 475°. What is the radius of the track? Homework Equations None that I know. The only thing I know is that the track is circular The Attempt...
  4. D

    What is the radius of the track

    This porblem has been killing me. It's the last question that I have left on my homework assignment and it is due tonight at midnight. The car in the figure below travels a distance of 745 m along the track, and the driver finds that she has traveled through an angle of 475°. What is the...
  5. J

    Canceling one electromagnetic wave with another for a part of the radius

    I was curious about electromagnetic waves and whether or not they can be canceled in the fashion I require. First I will state a few principles that I am considering in the paragraph below and the paragraph after will pose the question in full. A Wireless router produces a signal that...
  6. D

    Which Latitude has the Smallest Radius?

    °Homework Statement I need to find which latitude has the smallest radius. 40°30'13" or 30°40'13" Homework Equations -None- The Attempt at a Solution I converted from DMS to degree and got: 40°30'13" ≈ 40.72° and 30°40'13" ≈ 30.88° Since the Earth is not a perfect...
  7. A

    Bohr radius and length contraction

    from wikipedia - "The Bohr radius is a physical constant, approximately equal to the most probable distance between the proton and electron in a hydrogen atom in its ground state." in Planck units bohr radius (a0) = (mp/me).(1/\alpha).(lp) the 1st 2 terms of the RHS of the equation are...
  8. E

    Determining the radius of curvature mass spectrometre question

    Homework Statement A mass spectrometer is an important tool in the study of air pollution. However, one of the difficulties faced by scientists is that carbon monoxide molecules (CO), which are major contributors to air pollution, have very nearly the same mass as harmless nitrogen molecules...
  9. A

    Find radius if a circle is inscribed in quadrilateral

    :cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry::cry:
  10. G

    Intuition for arc length, angle and radius formula

    I don't understand the intuition/proof of why arc length = arc angle * radius. This may be partially because I don't fully understand the concept of radians, but anyhow please help.
  11. H

    Pressure of liquid given radius, help please

    A test tube filled with water is being spun around in an ultracentrifuge with angular velocity. The test tube is lying along a radius and the free surface of the water is at radius r(o). Show that the pressure at radius r within the test tube is: p = .5(p)(angular velocity)^2(r^(2)...
  12. L

    Calculating Stellar radius from bolometric flux

    Homework Statement The monochromatic flux emitted from unit surface area of a black body is given by F_{\lambda}(T) = \frac{2h\pi c^{2}}{\lambda^{5}} \frac{1}{exp(hc/\lambda KT)-1} Wm^{-2}m^{-1} If the distance to star X is 620 parsecs, calculate: (a) the radius of star X, in...
  13. R

    Radius of convergence without complex numbers

    Pretend that you are expaining the following to someone who knows nothing about complex numbers and within a universe where complex numbers have not been invented. In examining the function f(x) = \frac{1}{1 + x^2} we can derive the series expansion \sum_{n=0}^\infty (-1)^n x^{2n} We...
  14. R

    Radius of Gyration: Physical Significance

    What is the physical significance of the radius of gyration
  15. X

    Calculating how long it takes for a comet to reach a sun of radius zero

    Homework Statement Consider the extreme case that the comet is released from rest at a distance R_max from the sun. In this case L is actually zero. Use the technique described in connection with 4.58 to find how long the comet takes to reach the sun. The radius of the sun for now is zero...
  16. G

    Area Under a Curve, 3D, with known end points and curve radius

    I am trying to find out a method of determining the area below a curve. The end points of the curve are known in cartesian space, and the curvature of the curve is known. A diagram of the curve is here, shown in the images belowthis webpage ß must be in radians Where; MD =...
  17. B

    DE: Lower Bound for radius of convergence

    Prb:(x^4+4*x^2+16)y"+4(x-1)y'+6xy=0 P=(x^4+4*x^2+16) Q=4(x-1) R=6x P=0 for - 1 - 3^(1/2)*i 1 - 3^(1/2)*i - 1 + 3^(1/2)*i 1 + 3^(1/2)*i Q=0 for 1 R=0 for 0 Do we ignore Q & R, plotting P, then find shortest distance which would equal 2?
  18. S

    How to solve for mass given gravitational force and radius ?

    how to solve for mass given gravitational force and radius ? Homework Statement The gravitational force between two identical objects 2.00m apart is 3.50x10^-6N. determine the mass of each object. the answer should be [458kg] Homework Equations i know that Fg= GmM/r^2 so...
  19. M

    What Is the Radius of Convergence for the Taylor Series of x/(1+x^2) at x=0?

    Hi everybody, Firstly sorry for my bad English . I have a question related to taylor series . I did not find easy way to solve it .Derivatives are becoming more and more complex . Please help me. question : Work out the taylor series of the function x/(1+x^2) at x =0 .Find the radius of...
  20. N

    Inverse relationship between radius and resistance

    Homework Statement We did an experiment using resistance putty and a multimeter. We changed the radius of the putty but kept the length the same. We recorded the resistances at different radius'. I know that physics theory says that resistance is inversely proportional to cross-sectional...
  21. A

    Particle oscillating around equilibrium radius

    Homework Statement A particle of mass m moving in three dimensions is attracted to the origin by the gravitational force of a much heavier object. It can be shown that the radial motion is governed by the following equation m\ddot{r}=-\frac{k}{r^{2}}+\frac{l^{2}}{mr^{3}} where k is a...
  22. D

    Dark matter density as a function of radius

    Homework Statement Evidence for dark matter comes from “flat” rotation curves of galaxies. Assume that the observed matter moves in circular orbits about the center of the galaxy and that the velocity of the matter as a function of the radius v(r) is a constant. Also assume the...
  23. H

    Fields and Schwartzchild radius for a black hole

    Homework Statement The Schwartzchild radius for a black hole is the distance from the singularity of the black hole at which the escape velocity is the speed of light. You wish to create a black hole, with radius of only 1.0m for personal research. How much mass would this required? Would the...
  24. K

    Considering volume of atom , what radius

    do you consider Covalent radius, Van der Waals radius or atomic radius?
  25. R

    Finding radius a of non-conducting spherical shell

    Homework Statement A non-conducting spherical shell is uniformly charged. The electrostatic potential \phi at the centre of the sphere is \phi1 = 200V The potential at distance r = 50cm from the centre is \phi2 = 40V Find the radius of sphere: a Homework Equations I seem to have...
  26. R

    What are the challenges in calculating the Bohr radius?

    Homework Statement the equation for the bohr radius is 4pi (permitivity of free space) * (reduced Planck constant)/ (elementrary charge)2(mass of an electron) The Attempt at a Solution let's just just focus on orders of magnitude: (10^-12 * 10^-34)/(((10^-19)^2)*(10^-31)...
  27. T

    Help with a Geometry Problem - Calculating The Radius of a Curve

    Hello all I work in transport engineering. i have come across what seems to be a simple maths problem but i do not understand it. The problem relates to geometry i.e. calculating the radius of a curve using a chord and a versine. The problem is this:- " a general rule of thumb is as...
  28. Y

    What is the average radius of a betatron vacuum chamber?

    My friend and I were discussing particle accelerators (betatrons to be exact) and we began to argue about the size of the core magnets and vacuum chamber. He said that an average torodial vacuum chamber is 0.5m. I have seen old photos of them and said that's more likely to be the diameter. I...
  29. T

    Plastically Deformed Steel Tube - Radius of Curvature to Straighten

    A hydraulic steel tube of diameter 10mm and wall thickness 1.5mm has been bent to a radius of 100mm. Calculate the reverse radius of curvature that needs to be applied to straighten the tube. M/I= σ/Y = E/R I am really struggling on the above question. I think I need to read off the...
  30. C

    Radius of curvature and focal distance question?

    Radius of curvature and focal distance question? Hi everyone! Really struggling on these two questions and have spent way too many hours coming up with the wrong answers. Below are the questions and my attempts. Any help would be greatly appreciated! 1. Calculate the radius of curvature...
  31. E

    Working out radius of sphere using Mass&Density

    Homework Statement Using mass = 2.473x10^23kg and Density = 7.481g/cm^3 work out the radius of said sphere,Homework Equations D=M/V 4/3∏r^3 The Attempt at a Solution D=M/V DV=M V=M/D Mass = 2.473x10^23kg V=2.473x10^23kg / 7.481g/cm^3 V=2.473x10^23kg / 0.007481kg/cm^3 V= 3.31x10^24 cm V=...
  32. S

    Find radius of bowl at certain height

    Homework Statement A bowl has radius of 16 cm at the top of it (the largest diameter) and diameter of 8 cm at the bottom of it (the smallest diameter). Find the diameter at position: a. 1/4 height b. 1/2 height c. 3/4 height Homework Equations not sure, maybe: trigonometry...
  33. P

    Complex Analysis - Radius of convergence of a Taylor series

    Homework Statement Find the radius of convergence of the Taylor series at 0 of this function f(z) = \frac{e^{z}}{2cosz-1} Homework Equations The Attempt at a Solution Hi everyone, Here's what I've done so far: First, I tried to re-write it as a Laurent series to find...
  34. A

    Ring of radius R and uniform charge

    Homework Statement At what distance along the central axis of a ring of radius R = 0.200 m and uniform charge is the magnitude of the electric field due to the ring's charge maximum? What is the positive solution for z? Homework Equations E = \frac{kqz}{(z^2+R^2)^(3/2)} The...
  35. P

    Comples analysis - Radius of convergence of a Taylor series question

    Homework Statement Find the radius of convergence of the Taylor series at z = 1 of the function: \frac{1}{e^{z}-1} Homework Equations The Attempt at a Solution Hi everyone, Here's what I've done so far. Multiply top and bottom by minus 1 to get: -1/(1-e^z) And then...
  36. P

    Change in GPE of the moon as the radius increases. Getting extreme answers

    Okay, first of all, sorry for not posting here, I unknowingly posted this q in the wrong section and got an infraction. Sorry againHomework Statement Question : Calculate the change in gravitational potential energy of the moon, when the radius of it's orbit increases by 4cm. Radius ...
  37. B

    Determining the Radius of the Moon (Ratio and shadow measurements)

    Hello. I have been going through some old OU books on the sciences and started working through an excercise when I came to a stumbling block. I have come here in the hope that someone may be able to shed some light on my problem. This is all for personal study as I am not enrolled on any...
  38. L

    Bodies of mass near the Schwarzschild Radius

    What happens to bodies of mass as they approach and get near this value? If they don't actually reach the criteria, will their properties be vastly different from bodies that do reach the criteria? Will it expand instead of maintain it's radius? I'm also wondering how much energy it takes...
  39. D

    Circular motion-what is the radius of the loop de loop in meters

    Homework Statement Snoopy is flying his vintage warplane in a "loop de loop" path being chased by the Red Baron. His instruments tell him the plane is level (at the bottom of the loop) and traveling at 180 km/hr. He is sitting on a set of bathroom scales that him he weighs four times what he...
  40. D

    Circular motion- radius of the plane's vertical loop

    Homework Statement An 80-kg pilot flies a plane in a vertical loop. At the top of the loop, where the plane is completely upside-down for an instant, the pilot hangs freely in the seat and does not push against the seat belt. The airspeed indicator reads the 110 m/s. What is the radius of...
  41. C

    Star Cluster Within Self Schwarzschild Radius

    I have a qualitative question to ask: The Schwarzschild radius of matter is proportional to its mass. The actual radius of the matter, assuming it is spherical, is proportional to the cube root of its mass. This implies that the density required to form a Schwarzschild radius decreases as...
  42. T

    I with finding the radius of convergence of a complex series

    Radius of convergence of the series n^2(x^n)/(3n!) I am stumped the question is: find the radius and interval of convergence of the following series {sum_(n=1)^(Infinity)}((n^2)(x^n))/(3*6*9***3n) I'm assuming that equal to ((n^2)(x^n))/(3n)! then lim_(n->infinity) of...
  43. E

    Use the density of the liquid to estimate the radius of a neon atom.

    Homework Statement Neon is a monatomic gas; Density = 0.900 kg.m-3 Pressure = 1 atm Temperature = 273K. Density of liquid neon = 1207 kg.m-3 (i) Calculate the volume occupied by one gram mole of neon at a temperature of 273 K and a pressure of 1 atm. (ii) Determine the atomic...
  44. jinksys

    Gauss's Law:Metal sphere of radius 'a' surrounded by a shell

    Homework Statement A metal sphere of radius a is surrounded by a thick concentric metal shell (inner radius b, outer radius c). Neither the shell nor the sphere carries any charge, but there is a point charge +Q located inside an irregularly shaped cavity in the otherwise solid sphere as...
  45. F

    Finding the radius of convergence of a series.

    Homework Statement What is the radius of convergence of the Taylor Series of the function f(z) = z cot(z), at the point z = 0? Homework Equations Taylor series is given by: \sum_{k=0}^{\infty} \frac{f^{(k)}(z_{0})}{k!} (z - z_{0}) And the radius R by: \lim_{n \to \infty}...
  46. 1

    Circle radius 0, algebraic manipulation

    Homework Statement Going over some old tests, I am asked to find the contour of the function: T = 100 - x^2 - y^2 at T = 100, T = 0, etc. I have a question regarding the contour at T = 100 Homework Equations The Attempt at a Solution Consider T = 100 100 = 100 - x^2...
  47. S

    Relating radius and angular freq of an rotating object

    Homework Statement an ball of mass m is connected by a string with spring constant k, to a rotating shaft. Find a relation between the radius of the circle, and the angular frequency. Homework Equations The Attempt at a Solution Let: Natural length of spring = x0...
  48. W

    What is the larmor radius of an electron in the inner van allen belt?

    Homework Statement What is the larmor radius of an electron in the inner van allen belt? This is for a General Astr class so I feel like I must be over complicating it. Electron Kinetic Energy in the inner VA belt: K≥30 [MeV] (much greater then its rest energy) VA Belt Radius: r~1.1-2.0...
  49. M

    Kinetic Energy's Effect on Electron's Radius in Magnetic Field

    An electron moves in a circular orbit of radius r in a magnetic field. The electron moves in a path perpendicular to the magnetic field. If the kinetic energy of the electron is doubled, what is the new radius of its path? What formula would I use to go about this? Is this about mass...
  50. M

    Help me find the radius of convergence?

    Homework Statement Ʃn!(x-1)n I need to find the radius of convergence for this summation from n=0 to n=∞ The Attempt at a Solution I started off with the ratio test: (n!(n+1)(x-1)(x-1)n)/(n!(x-1)n) = (n+1)(x-1) (x-1)lim(n+1)...Now at this point it looks to me like the series does...
Back
Top