Axis Definition and 928 Threads

http://photoblog.msnbc.msn.com/_news/2011/03/12/6256280-how-the-quake-shifted-japan?chromedomain=cosmiclog I thought this was pretty fascinating. According to this, the Earth's rotation has increased in speed as well, by 1.8 microseconds.

Homework Statement The moment of inertia (in4) about the y-axis is most nearly (a) 39,500 (b) 37,600 (c) 38,700 (d) 36,400 Homework Equations Iy(circle)= .25(pi)(r^4) Iy(triangle)= (1/12)h(b^3) parralel axis theorem= Iy=Iy'+A[d(x)]^2 The Attempt at a Solution Iy(circle)=...

Homework Statement Hellow guys i am stuck at this problem, you can see how far I have done, could someone show me how I can complete the square of this problem and how it is integrated, thanks! http://img98.imageshack.us/i/img0003lz.jpg/ Homework Equations The Attempt at a...

Homework Statement A thin rod has mass M and length L. What is the moment of inertia tensor about the center of mass if placed along the x axis. Homework Equations I would write the inertia tensor in component notation, but I don't know how to use Latex. The Attempt at a Solution...

Hi everyone, this isn't really a homework question- this integral has come up during project work- but this seems like a sensible place to ask it nontheless. Homework Statement Compute I(t)=\int^{\infty}_{0} dx \frac{x^5}{(t+x^2)(1+(t+x^2)^4)} where t is real and positive. Homework...

say i have a lever, fixed to an axis in its right end. now a perpendicular force is exert on the lever, from its left end. the lever will obviously rotate relatively to the fixed axis. (the force will rotate with it, and will always be perpendicular to the lever. so the lever has a fixed...

Homework Statement A cylindrical shell of radius 9.9 cm and length 286 cm has its charge density uniformly distributed on its surface. The electric field intensity at a point 23 cm radially outward from its axis (measured from the midpoint of the shell ) is 44800 N/C. Given: ke = 8.99 × 10^9...

What effect does rotation have on a sphere moving through a fluid (liguid or gas) when traveling along the axis of rotation? The simplest being an up or down motion.

Homework Statement Show that the field on the x-axis for the dipole (negative on the right, positive on the left separated by 2a) is given by the equation E = kq / x^3 for x >>a. Homework Equations Coulomb's Law F = kq1q2 / r^2 E = F/q = kQ / r^2 The Attempt at a Solution Since...

Homework Statement Hi friends, I have uploaded the problem and picture at the link below. Please take a look. http://img64.imageshack.us/img64/4753/sam0247i.jpg Homework Equations F(vector) = F(cos\alphai + cos\betaj + cos\gammak) Ma = u_a(vector) \bullet M_o (vector) = u_a \bullet (r x F)...

Hi all, this is my first post, so forgive me if this is in the wrong forum. (I believe it does belong here) We are currently doing moments in physics and I have seen this in a few homework problems but can't seem to grasp it. For example, in one question, we are given a new axis AA that...

Homework Statement For a rectangular, uniform wing or beam, where would the location of the elastic axis be relative to the mid-chord position? Also, what's the difference between semi-chord and mid-chord for a uniform rectangular wing? Thanks in advance for any help, Carl

Hi, I am working through the Feynman lectures on physics and trying to calculate the moment of inertia stated in the title. (the taxis of rotation going through c.m., orthogonal to length). My approach is to slice the cylinder into thin rods along the length, using the parallel taxis theorem...

I am currently trying to understand the idea of quantum entanglement (more specifically the Bell inequality). But its brought up a lack of my knowledge of spin. So, I am trying to figure out how spin can be projected onto an arbitrary axis. Suppose there are two entangled electrons of...

Homework Statement Find the transformation matrix R that describes a rotation by 120 about an axis from the origin through the point (1,1,1). The rotation is clockwise as you look down the axis toward the origin. Homework Equations Rotations about the z-axis are given by R_{z}(\alpha) =...

Homework Statement A force is rotating the rod of mass m and length l round it's endpoint, according to drawing. The force rotates either, so as to simplify the problem. What force, apart from the one opposed to the centrifugal force, acts at the bearing? Homework Equations M=I\alpha...

I'm really confused with how to prove this result...could anybody help please? Let I_{1} be the line segment that runs from iR (R>0) towards a small semi-circular indentation (to the right) at zero of radius epsilon (where epsilon >0) and I_{2} a line segment that runs from the indentation...

I searched through the forums and couldn't find a topic or answer, so I will pose it (possibly again). I can work through deriving the equations of motion (either through Euler-Lagrange methods or Hamilton methods) for the spinning book problem and it is obvious that there *is* an unstable axis...

Let's say I have a uniform rod lying on a table in a frictionless environment. Now I throw a ball with a certain velocity at one end of the bat. How can I describe the motion of that bat. I need to make it seem like it is going in a circle. I know it will move back and rotate but I don't know...

Homework Statement A 40 uC charge is placed on x-axis at x=4cm. Where should a negative 60 uC charge be placed to produce a net electric field of zero at the origin? Homework Equations Fe=Ke((q1*q2)/r^2) The Attempt at a Solution I tried rearranging this equation to solve for r

Homework Statement A wheel is comprised of two 50.0 cm long thin rods of negligible mass and a thin metal ring with a mass of 10.00 kg, mounted on a very low friction bearing. A 100 gram lead weight is shot horizontally at the stationary wheel with an initial speed of 50.0 m/s and sticks to...

Homework Statement 6x^2-6xy+14y^2-45=0 Two recording devices are set 2400 feet apart, with the device at Point A to the west of the device at point B. At a point on a line between the devices, 400 feet from point B, a small amount of explosive is detonated. The recording devices record...

Say I have an X-ray binary system of a B2 main-sequence star with an unseen companion (i.e., black hole). They have a separation of 20 million km and an orbital period of 4 days. How do I figure out what the semi-major axis is? I need it for the formula for Kepler's Version of Newton's Third...

Homework Statement A solid door of mass 37.80 kg is 2.30 m high, 1.70 m wide, and 2.53 cm thick. What is the moment of inertia of the door about the axis through its hinges? Homework Equations I= Icm + MD^2 Icm = 1/12[M (a^2 +b^2 )] formula for inertia of a rectangular plate. The...

Note this is physics I This should be the right section as this is not homework.. Ok I'm having trouble understanding the concepts of rolling without friction, kinetic energy linear and kinetic energy rotational. I have a hard time following my professor in class and usually like to go...

Hey guys, I am having some trouble understanding this problem. The horizontal x-axis is drawn through the centroid C of the area shown, and it divides the area into two component areas A1 and A2. Determine the first moment of each component area with respect to the x axis...

Homework Statement What is the moment of inertia of a solid cylinder (of mass 8.41kg and radius 7.5cm) rotating about an axis parallel to the symmetry axis but passing through the edge of the cylinder?Homework Equations I=.5mr2, but how does this change when the axis is passing through the edge...

Homework Statement A wheel of diameter 26.0 cm is constrained to rotate in the xy plane, about the z axis, which passes through its center. A force F = ( - 31.0 i + 49.0 j )N acts at a point on the edge of the wheel that lies exactly on the x-axis at a particular instant. What is the...

Homework Statement How do I find the angle between r and the X axis?Homework Equations The Attempt at a Solution My attempt is here: https://www.physicsforums.com/attachment.php?attachmentid=29307&d=1287751693 However the computer says 69.3 degrees is incorrect.

Hello! I'm very new to MATLAB and came across a problem: I need on the X axis values from 1 to 1024, only the powers of 2. I managed to get MATLAB to show only these values but as they would be when all the values are shown (1 and 2 are one ever the other and 512 and 1024 are far away one from...

Homework Statement Four identical particles of mass 0.475 kg each are placed at the vertices of a 1.73 m x 1.73 m square and held there by four massless rods, which form the sides of the square. What is the rotational inertia of this rigid body about an axis that (a) passes through the...

Homework Statement How do you find the angle between the resultant and the x-axis? Please refer to the link in the picture. I just don't know how to get theta which is 10.26 degrees. Homework Equations https://www.physicsforums.com/attachment.php?attachmentid=29314&d=1287763774 The...

Suppose we have a uniform disk and two forces are acting tangentially at the rim (both pointing in the same direction and parallel to each other and at diametrically opposite ends of the disk). Since the disk does not rotate the sum of torques about an axis passing thorugh the center of the...

Electric potential at point x on the axis of a ring of charge density "eta" Homework Statement A circular disk of radius R and total charge Q has the charge distributed with surface charge density \eta = cr, where c is a constant. Find an expression for the electric potential at distance z on...

I'm not sure if this is the right place for this question, but I didn't see a forum specifically about software. I'm trying to define a function in MathCAD that describes the rotation of a body vector about an axis u by an angle ɸ. What I've typed in is: R(ɸ,u):= [ 3x3 matrix where each...

I'm working on a complex analysis problem from Arfken. Integrate[ (cos(b*x)-cos(a*x))/(x^2), {x, -Infinity, Infinity}] and show that it is equal to Pi*(a-b) Attempt: I first look at a related problem (or one that I think is related). => f(x) = sin(x)/x => f(z) = sin(z)/z...

Hello Everyone, Below are three questions relating to the integration between curves that have been bugging me for some time now. I know how to integrate between curves. I know how to integrate between x and y, but when given equations like the ones below I am lost as to how to figure out 2...

A chiropractor performs a lumbar spinous pull manipulative procedure. Using instrumentation , she determines 3D coordinates of the axis of rotation of the contacted verebra at t = 15 msec relative to the local axis system as shown. A uniaxial load cell at the spinous process measures a force...

Homework Statement As per Griffiths 3.21, I am given the on axis potential a distance r from a uniformly charged disk of radius R as a function of \sigma. Using this and the general solution for laplace's equation in spherical coordinates with azimuthal symmetry, calculate the first three...

I need to write the letter p with a circumflex over it for an axis lable on a graph in matlab. Any ideas how I can do this?

Hey PhysicsForums. Long time reader looking for some assistance Homework Statement [PLAIN]http://img205.imageshack.us/img205/3923/physicsg.jpg 2. The attempt at a solution I'm pretty sure the idea is to find the unit position vector to point A, and the force vector F. I found...

Homework Statement What is the moment of inertia of the plate about z axis? Homework Equations The Attempt at a Solution Consider the isosceles triangle to be a part of a square of side l/root(2) Its mass will be 2M We know that its moment of inertia about the centre...

1. (a) A particle has ~r(0) = (4 m)j and ~v(0) = (2 m/s)i. If its acceleration is constant and given by ~a = −(2 m/s2) (i+j), at what time t does the particle first cross the x axis? Answer in units of s. (b) At what time t is the particle moving parallel to the y axis; that is, in the...

Homework Statement A ball P of mass m kg is dropped from a point A, which is 2 m vertically above a point B on a horizontal floor. After P hits the floor at B, it rebounds and hits another ball Q, of the same mass, which has also been dropped from A. The impact between the two balls is...

Hello. Can anyone tell me what is the "axis of figure" or "figure axis" ? This is in the context of rigid bodies, rotation, and moment of inertia.

Principal axis about a section... HELP! Homework Statement a, Calculate centroid inclination of principal axis of section b, Now calculate principal 2nd moment of area c, Cargo nets produce a moment (my) about a section (Y axis only). If max bending at point A cannot exceed 380 N/mm^2, what...

Homework Statement 2\pi \int_0^6 y\sqrt{25- (y- 1)^2}dy + 5\pi That's the integral i need solved 2. The attempt at a solution[/b] so first i subbed u=y-1 took the 2 pi out of the integral that got me 2 integrals u*sqrt(25-(u)^2) du + sqrt(25-(u)^2) du the first integral =...

1. Homework Statement k so here is the equation i need help with that will find me the volume of a sphere 2*pi*y*sqrt(25-(y-1)^2) dy - 5*pi from 0 to 6 the 5 pi is the volume of a cylinder 2. Steps so first i subbed u=y-1 took the 2 pi out of the integral that got me 2 integrals...

Hi..I have a basic question regarding the equation of an ellipse. Let's say I ahve an ellipse with major and minor axes 2a and 2b respectively. Now, to check whether a point lies inside this ellipse, its fairly simple...I can just use the standars ellipse equation for that. Now, if my major axis...

1. Hi all, I'm doing a simulation on 3 different cantilever beam as shown in the attached figure. a) is the beam with only width varying from the base to the free end (height stay constant along the beam) , b) is the beam height varying from the base to the free end (width stay constant along...