Axis Definition and 928 Threads

  1. S

    Magnetic field at (z) axis of square loop

    Homework Statement We have a square loop with side length 2a, at xy plane. Now we know ( I have calculated ) that the magnetic field at the center of the square loop to be H = \frac{2I}{\sqrt{2} \pi a} Now we want to know what is the magnetic field at point P, which is on the axis which...
  2. B

    Help drawing Mohr's circle with rotated axis

    Homework Statement Plane stress in xy-plane. Use Mohr's Circle to find σx1 σy1 and τx1y1 if the XY axis is rotated counterclockwise θº I want to do my HW problem myself so I'll just put some sample values. If i know how to get this one, i'll know how to do the HW problem(s). (Units won't...
  3. X

    Torque Sum with applied torque off axis

    I think I'm missing something really simple here due to being out of school for a while: In a free body diagram, if I am trying to take the sum of torques about point 1, how should I deal with an applied torque at point 2? See attached sketch
  4. V

    Calculate the angle of the neutral axis from the x-axis

    Homework Statement Calculate the angle of the neutral axis from the x-axis when the beam is loaded with a positive couple of 6kNm acting around the X-axis Homework Equations i have calculated: Ixx: 2854758.6 mm^4 Iyy: 1429034.6 mm^4 Ixy: -1143476 mm^4 The Attempt at a Solution...
  5. twoski

    Finding Volume of Solid Rotated Using Washers and Disks

    Homework Statement Using disks or washers, find the volume of the solid obtained by rotating the region bounded by the curves y = x^2 and y = 4 about the line y = 4 The Attempt at a Solution Since y=4 is parallel to the x-axis i assume i should be using the 'washer' method. The points of...
  6. K

    Finding the semi-major axis of a transfer orbit?

    Homework Statement Hi, I have a question on my homework that I'm absolutely stuck at. I'm not sure how to go about this. Can someone help me through the steps to solve it? there are more after this similar to it so learning how to do this one would help me do the other ones by my self. Thanks...
  7. V

    Second moment of area about the horizontal axis

    Could someone help me on how to calculate the second moment of area of the beam in the figure below? Thank you
  8. P

    Angle on coordinate axis, related acute angle

    Homework Statement Tan A = -2/6 a) Draw two possible locations on the coordinate axis for the terminal arm of angle A b) Find two possible values for the measure of angle A and the related acute angle. Homework Equations c^2 = a^2 + b^2 SOHCAHTOA The Attempt at a Solution I know...
  9. Z

    Rotation of a uniform rigid disc about a fixed smooth axis

    Homework Statement A uniform circular disc has mass M and diameter AB of length 4a. The disc rotates in a vertical plane about a fixed smooth axis perpendicular to the disc through the point D of AB where AD=a. The disc is released from rest with AB horizontal. (See attached diagram) (a)...
  10. C

    Moment of Inertia: Object w/ Rod & Sphere

    Homework Statement An object is formed by attaching a uniform, thin rod with a mass of mr = 6.91 kg and length L = 4.88 m to a uniform sphere with mass ms = 34.55 kg and radius R = 1.22 m. Note ms = 5mr and L = 4R. What is the moment of inertia of the object about an axis at the left end...
  11. Y

    Rotation matrix arbitrary axis?

    Hello everyone. I'm having some trouble with rotation matrices. I'm given three matrices J_1, J_2, J_3 which form a basis for the set of skew-symmetric matrices (\mathfrak{so}_3). Further, the matrix exponent function is such that exp[\alpha J_i]=R_i(\alpha), so taking the...
  12. L

    Parallel Axis Theorem | Kinetic and Potential Energy

    Homework Statement A rigid body is made of three identical rods, each with length L = 0.525 m, fastened together in the form of a letter H, as in Figure 10-56 below. The body is free to rotate about a horizontal axis that runs along the length of one of the legs of the H. The body is allowed...
  13. B

    Torque, point or axis of rotation

    Hi, 1) Do we calculate torque with respect to a point or with respect to an axis? I have read them both in different resources, and so I am confused! 2) If we calculate torque with respect to an axis, many introductory textbooks discuss the motion of the gyroscope by considering how the...
  14. C

    What Is the Electric Field Produced by a Uniform Line Charge on the x-axis?

    Homework Statement Charge is uniformly distributed along the x-axis with density ß. Use Gauss' Law to find the electric field it produces, and use this to calculate the work done on a charge Q that moves along the y-axis from y = a to y = b. Homework Equations...
  15. R

    What Is the Axis of Rotation for This Matrix?

    Homework Statement consider the following rotation matrix: 0 0 1 1 0 0 0 1 0 Find the axis of rotation. Homework Equations The Attempt at a Solution I know the following: Ω|1> = |2> Ω|2> = |3> Ω|3> = |1> where Ω is an operator. It is a cyclic permutation. What do not understand is...
  16. Astrum

    Mass revolving around a vertical axis

    Homework Statement Problem in the attachment Homework Equations -r(dθ/dt)^2= Centripetal force F=ma The Attempt at a Solution The tension force will be cut into two parts. I split the distance between the two strings into two sections, so the distance "r" to the mass can be...
  17. Y

    Finding the major and minor axis of ellipse

    An ellipse is represented by \rho(t)^2=x^2(t) + y^2(t) where \rho(t) is the distance from origin to the ellipse at a given time. The way the article used to find the major and minor axis is the take the derivative \frac{d(\rho^2(t))}{d t}=0 to find the maximum and minimum. My question is why...
  18. J

    Change in Earth's axis and Rotation due to tectonic activity

    Since the redistribution of mass in the Earth's surface can be caused by earthquakes, sometimes the Earth's rotation is increased or decreased by a small amount. Recent series of quakes seem to be related. To me, this makes sense, since if plate "A" should move, then plate "B" would also...
  19. C

    Resolved resultant force along a specific axis

    Homework Statement http://img687.imageshack.us/img687/8767/meprob27.jpg If the resultant force acts along the positive u axis, determine the resultant force and angle theta (red angle) Homework Equations law of sines pythagorean theorem, etc trig parallelogram, head to tail methods...
  20. P

    What is the meaning of the y-axis on a sine wave graph?

    Okay this has been bothering me, I know what the x-axis on sine graph mean, but not the y axis. I know when I type for example: sin(pi) I will get 1. But what is that 1? I know its the y cordnate. But what is it?
  21. K

    Resultant vector relative to x and y axis.

    I was wondering if someone could have a look at my attempt at calculating the resultant vector of 3 forces. Figure is here:http://tinypic.com/view.php?pic=2psrllz&s=6, and from the top down the forces are F1=24,9kN, F2=12,7kN and F3=21kN. The angles are(again from the top down) 56,4°, 15,3° and...
  22. H

    Invariance of the y coordinate for a boost along the x axis

    Homework Statement I've been reading through Spacetime Physics by Taylor & Wheeler, but this argument about the invariance of the y coordinate for inertial frames, one moving relative to the other on the x axis, is tripping me up. I'll just write the text word for word: I'm just not...
  23. leviterande

    Will a ball on a string spin around its own axis when released?

    Hello! I couldn't find any answer to a wondering I have: On one end of a light string, attach a heavy ball, and on the other end of the string hold it with your hand and whirl around the ball-on-string. You reach a high rotational speed and finally the string breaks at the string-ball...
  24. Y

    Finding the length of the major and minor axis of ellipse.

    \vec E\;=\; \hat x E_{x0}\cos(\omega {t} -kz)\;+\;\hat y E_{y0}\cos(\omega{t}-kz+\delta) For z=0, this is a vector that trace out an ellipse with time t. I want to 1) to verify that using the definition of differential calculus, we can find the length of the major and minor axis by...
  25. S

    How to calculate the solid angle of a cone with cone axis arbitrary?

    I read that if the cone with apex angle 2α whose central axis is vertical, apex at the origin, then one can use spherical coordinate to calculate the solid angle of the cone ∫02∏∫0αsin\varphid\thetad\varphi However, what if the central axis is align to y-axis horizontally, instead of...
  26. A

    Why do we choose to have perpendicular axis?

    Why do we have x-axis perpendicular to y-axis? Why not 45° or something else? Even if we keep any other angle other than 90° we can still build up all other vectors using them in the plane. So what is there is 90° that makes it special and simpler?
  27. J

    What is the axis label for the fourth dimension?

    I have a quick question. On a typical cartesian coordinate system you have the x-axis and y-axis for two dimensions and the z-axis for the third. What would you label the axis representing the fourth dimension? I know this is a bit of a silly and unimportant question, but I was thinking...
  28. T

    Volume generated by revolving curve around axis

    Homework Statement Find the volume generated by revolving the regions bounded by the given curves about the x-axis. Use indicated method in each case. Question 11: y = x^3, y = 8, x = 0 Question 15: x = 4y - y^2 - 3, x = 0 Homework Equations for question 11: Shells for Question 15...
  29. 2

    Does an electron actually spin around its axis?

    I am a High School student and I was told that magnetic field appears whenever you align the electrons around the atoms (when they spin in the same direction around their axes). Is this true or do schools actually mislead people?
  30. T

    Volumes by Slicing and Rotation about an Axis.

    Homework Statement Find the volume of the solid generated by revolving the region between the parabola x = y^2 + 1 and the line x = 3 about the line x = 3. Homework Equations The answer is found by integrating with respect to y with disk method, but I don't understand why my answer is...
  31. C

    Two dipoles on an axis. There is one point where the E field vanishes.

    Homework Statement THE ANSWER IS CHomework Equations None given. Pondering: E=(1/(2(pi)εnaught))(σ/z^3) p=qd U=-p dotprod EThe Attempt at a Solution We have attempted many variations of the above equations to try and find the answer. We are just seeking a point in the right direction as we...
  32. R

    Current Concentrated Along Axis

    Griffiths brings up a point that it might make sense that current in a fat wire would want to concentrate itself mainly along the axis of the wire, given that parallel wires attract each other. He then asks us to figure out why this might not happen, but to be honest I would think it should...
  33. N

    QM: Understanding Quantization Axis for 2-Level Atoms

    Hi I have a question on how to work with quantization axis. The setup I am looking at is a single two-level atom placed at the origin (0, 0, 0), which is not perturbed by any magnetic field. I now send in a laser resonant with the transition of the atom. With a right-handed coordinate...
  34. D

    MHB Incorporate axis symmetric case

    With this code, I can't look at the $\mathcal{J}_0$ or $\mathcal{Y}_0$. How can I altered to to pick up those orders? ClearAll["Global'*"]; inits = Table[ FindRoot[ BesselJ[n, x]*BesselY[n, 2*x] - BesselJ[n, 2*x]*BesselY[n, x] == 0, {x, n + 3}], {n, 1, 5}]; g1 = x /. inits zeros...
  35. J

    Finding B-Field Of Solenoid Slightly Off Axis?

    If you have a solenoid positioned along the z axis... ...how would one find the b-field at slight deviations of x and y? I have been googling for hours and can't find anything other than the fact that it is very difficult! Thanks guys!
  36. W

    Why is this length included when finding moment about an axis

    Homework Statement I have to find reaction at the joints but that's not important. I'm having trouble understanding what the book is doing but first allow me to explain the diagram so there is no confusion because 3D pictures are kinda hard to draw. In the first diagram there is a crank shaft...
  37. T

    MATLAB How to Set Axis Limits for an Added Graph in MATLAB?

    Hi, I am plotting 3 graphs in MATLAB using plotyy as [ax h1 h2] = plotyy(x1,Ftemp,x2,Fsnow); hold(ax(2), 'on'); h3 = plot(ax(2),x1,Fprec); I am thus adding the third graph to the right hand y-axis. I then set the limits and tickmarks for the right hand y-axis as set(ax(2), 'xlim'...
  38. D

    Axis angle rotations and changing rotation values

    I have two 3d applications and when an object(a cube for example) is transferred between them, the rotation values of the cube change(the object stay at the same location. translation and scale values stay the same) and I can't find why that occurs and it's driving me crazy. app 1 rotation...
  39. M

    Moment of Inertia for 3 masses, on an axis

    Homework Statement [refer to picture, thanks] The "L-shaped" figure rotates on the axis which which intercepts through 9 kilogram and 2.5 kilogram masses. Find the moment of inertia of the object for this type of rotation. Disregard the masses of connecting bars. Homework Equations MR^2...
  40. M

    When are two equal and opposite forces about an axis not a couple

    Homework Statement A current flows in vertical square coil whose plane is at right angles to a horizontal uniform magnetic field B. The coil can rotate about a vertical axis. Which is correct A) The forces on the two vertical sides are equal and opposite. B) A couple acts on the coil C) No...
  41. Jonathan Scott

    Redshift of spinning star surface as seen on axis

    I think I heard long ago that the redshift of all parts of the surface of a spinning star as seen from a distant point on the axis is expected to be the same, at least in theory, because of the following argument. Please can anyone confirm or refute this? A body which is capable of being...
  42. F

    Python Python, matplotlib plot 2D histogram on polar axis.

    Any python/matplotlib experts out there?? This one has been driving me crazy all day. I have three vectors, azimuth, frequency and power, which I would like to histogram and plot on a polar axis. I can plot a scatter plot this way no problem but the histogram gets messed up somehow. An example...
  43. S

    Understanding spin and axis in quantum entanglement

    I don't have a good grasp of "spin along axis" topic, so pardon my dumb questions: 1. Does a photon/electron have a different spin across each of the 3 axis? i understand that the spin of an electron/photon is not the same as that of, say, a ball 2. Gravity can distort time-space (and hence...
  44. N

    Object rotation about a fixed axis? question about derivatives in this problem?

    Object rotation about a fixed axis?? question about derivatives in this problem?? An object rotates about a fixed axis, and the angular position of a reference line on the object is given by θ=0.40e^(2t), where θ is in radians and t is in seconds. Consider a point on the object that is 4.0 cm...
  45. C

    Carnival ride : chair swings from cable attatched to overhang, spinning on axis

    Homework Statement The chair is 10 m from the rotating vertical axis. The solid overhang stretches 6 meters from the axis. (making 4 m from end of overhang to chair on the radial axis). The chair spins at a constant speed at 1 revolution per 10 seconds. Find the angle θ the cable makes with...
  46. S

    Rotate a Circle Around the X/Y Axis - Cylindrical Shells

    Homework Statement Rotate the region bound by the given curve by about the x and y axis. Find the volume through the cylindrical method. x^2 + (y-1)^2 = 1 Homework Equations Cylindrical method: ∫2∏xf(x)dx Slice Method: ∫A(x)dx The Attempt at a Solution x^2 + (y-1)^2 = 1 x =...
  47. R

    FInding the area of pentagon (on x,y,z axis) using trinagles?

    Hi, I need to do this for some homework and I don't really understand... could anyone help with the following question: Find the area of the pentagon PQRST with vertices P = (1,1,1), Q = (5,−3,1), R = (9, −1, −5), S = (2, 6, −5), T = (1, 2, 0). Hint: divide the pentagon into triangles...
  48. karush

    MHB Online calculators that have radians on the x axis

    just curious if anyone knows where there is online graphing program that will graph trig function with radians on the x axis tried Wolfframapha but not thanks ahead
  49. S

    Conservation of angular momentum axis

    Homework Statement about what point and about what kind of axis can we conserve angular momentum?can we conserve it about a point moving in circular motion? Homework Equations The Attempt at a Solution its just a understanding based question to apply to problems
  50. G

    How to Calculate the Moment of Inertia of a Thin Rod About an Off-Center Axis?

    Homework Statement Calculate by direct integration the moment of inertia for a thin rod of mass M and length L about an axis located distance d from one end.Homework Equations I = Ʃmir2i Which can be rewritten as int (r2)dm as Δm -> 0 Since we cannot integrate over a mass, we need to switch...
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