Axis Definition and 895 Threads

I have recently been reading that the Earth's Axis has tilted 26 degrees further with two of the most significant shifts occurring in December 2006. I read about this and thought... can this be true...how odd that I have been feeling like the sunlight this season seems to be reaching places...

Homework Statement Find the 3 × 3 matrix A such that its transform is the 120 degrees rotation in R3 about the axis through the origin and the point (1, 1, 1). Homework Equations Rotation Matrix in R2: R = (cosx, -sinx sinx, cosx) The Attempt at a Solution My...

Homework Statement I have a cylinder, for which i want to find the inertia tensor. http://www.mip.sdu.dk/~pino/inertiacyl.JPG Where the rotational axis are either the x (red) or y (green). Homework Equations I know that the inertia tensor for a cylinder is of the form...

i only joined this site to post this thing... now today at school (im in gr 10 by the way) a gym teacher came up to me with a football (american) in his hand and said "bassbreaker (not really my name but we'll leave it at that) You're a smart kid, tell me how this happens." and he rotated the...

Homework Statement A uniform square board ABCD had mass 5kg and sides of length 60cm. The board is hinged at A so that it can rotate freely in a vertical plane. A light string of length 1 metre is attached to B and to a point E, 80cm above A. The bards rests in equilibrium with AB horizontal...

Homework Statement A lever of length 3L can rotate freely around a horizontal axis O. The end of each arm "2L" and "L" of the lever has one mass : "4m" and "9m" , respectively. Find the velocity of mass "9m" at the bottom. Consider that the lever was initially at rest in the horizontal...

Homework Statement Find the volume of y = 2x^2 y = 0, x = 2 when it is revolved around the line y = 8.Homework Equations Integral formulas for volumes by discs, washers and cylinders.The Attempt at a Solution Translate the curve so that axis of revolution is along the X axis. Is this the...

Hi, I have this homework question and I completed and found the the foci and the center for the ellipse, but I don't understand how to find the semi major and minor axis. Graph and give the center, semi major and semi minor axis and foci of the ellipse 25x^2 + 350x + 9y^2 - 54y +1081 =...

In a motion about a fixed axis, where the position is r(t) and the angular velocity is w(t), we know that dr/dr = w(t)xr(t). My question, does this equation remains true if the axis vector is changing by the time t? Why so? Thank you.

Homework Statement The question si the make a rotation of axis to elmininate the cross-product term in the work i provided in this pic: http://img295.imageshack.us/img295/9579/untitledtu4.png Homework Equations The Attempt at a Solution I've drawn of the example in the pic I've...

Hi all, I'm trying to compute the axis forces in the construction I put to attachment. I already have computed the R forces, but I don't know where should I start computing the axis forces from, from which point. Could please someone give me some advice? Thank you very much, best regards.

A thin, uniform rod is bent into a square of side length "a". If the total mass is M, find the moment of inertia about an axis through the center and perpendicular to the plane of the square. Use the parallel-axis theorem. According to Parallel Axis theorem: I = I(cm) + Md^2 The...

Homework Statement A uniform stick of mass M = 2.1 kg and length L = 1.3 m is pivoted at one end. It is held horizontally and released. Assume the pivot is frictionless. Find the magnitude in Newtons of the force Fo exerted on the stick by the pivot immediately after it is released. I...

Hello, I have a three axis accelerometer that I am using in project that I am working on and I need to find the angle/vector of the axis’s when the device is not orientated to its designated axis, and when it is accelerating. If I lay the device flat on a horizontal surface and read the...

Homework Statement The rectangle shown has a mass, m. The sides are made of uniform thin wire. The short side is of length a, and the long side is of length b. If m = 5.50 g, a = 0.05 cm and b = 0.1 cm, what is the moment of rotational inertia about the axis indicated? (ignore the x's)...

Homework Statement Explain why applied force is plotted on the vertical axis of the graph even though it is the independent variable in a Hooke's Law experiment (involving a mass being attached to the spring) Homework Equations Fx = kx The Attempt at a Solution Maybe it's because...

Homework Statement The rod of length 2a swings and it rotates \dot{\phi}[/tex]. Find kinetic energy. The Attempt at a Solution I know how to find kinetic energy if we have rotation just in xy plane, but I'm having a problem to understand how to do it with rotation around y axis. If we have...

Hi, I was wondering in a cubic equation such as x³ - 5x = 2x - 1 can be rearranged to x³ - 7x + 1 = 0 is that 0 the y value, and +1 where the line crosses the y axis? Is - 7x the gradient or is x³ - 7x the gradient? Thankyou

find angle and axis of rotation that sends [x1,x2,x3] to [x2,x3,x1] I am not sure where to begin with this.

Homework Statement Rigid rods of negligible mass lying along the y-axis connect three particles (Fig. P10.20). The system rotates about the x-axis with an angular speed of 2.90 rad/s. Figure P10.20 (a) Find the moment of inertia about the x axis. ______kgm2 Find the total...

If someone could tell me how to go about it, I'd really appreciate it. Just point me in the right direction please. Kinda stuck. The vertex of a parabola is (-3,1) and it touches the x-axis at the origin. Find the equation of the axis of the parabola.

Given this problem: Find the volume and describe the shape of the object formed by the function f(x) = ½ x²+2 when the function is rotated around the x =3 axis and bounded by th region between the x = 0 and x = 4. I am not sure if I am thihnking about this correctly. I know in order to...

An eprint paper published today on the ArXiv and submitted to MNRAS: The Axis of Evil revisited by Land and Magueijo. The analysis of the CMB data is statistical by nature and the existence or non-existence of features such as the 'Axis of Evil' is a matter of evaluating its statistical...

Two masses (M1 and M2) are connected by a thin massless rod of length L. a) Determine the location of an axis perpendicular to the rod) which minimizes the moment of inertia of the system. The answer is "with M1 at the origin x = M2*L/(M1+M2) I know that I = Sum of ( M1*r1^2)...

Hi, I'm really confused about these 2 problems to the extent that I have no idea where to start. Any kind of suggestions and hints would be really appreciated. Thanks A 1090-N uniform beam is attached to a vertical wall at one end and is supported by a cable at the other end. A...

In my thermo text, they consider a diatomic molecule that is rotating about the axis joining the two atoms (also the axis of symetry) and make a quantum argument involving the energy levels of a rigid rotator to conclude that kT<<\Delta E for this particular degree of freedom. But isn't this...

Hi, This is my first time posting on this site and I was wondering if someone could help me with this question: A 200 g model rocket shown in Figure Ex13.24 generates 4.0 N of thrust. It spins in a horizontal circle at the end of a 100 g rigid rod. What is its angular acceleration? (I have...

Rotational Motion on an Axis Problem: Helpppp? Problem: Two thin rectangular sheets (0.20 m x 0.40 m) are identical. In the first sheet the axis of rotation lies along the 0.20-m side, and in the second it lies along the 0.40-m side. The same torque is applied to each sheet. The first sheet...

Could anyone please tell me what angle I need to find when the question asks to find an angle with respect to x axis. (or y axis) Thank you.

What is the significance of the polar axis? What would it mean if someone said 'Take the z axis (in 3D cartesian coords) as the polar axis?'

Hi, I have a little question The precession axis of a spinning top is represented vertical in every pages I have seen. Why is that? Isn't that axis just a virtual (resulting from spinning of the precession axis) precession axis, because the precession axis must be perpendicular to momentum...

A particle moves along the x axis. Its position is given by the equation x = 1.90 + 3.10t - 4.15 t2 with x in meters and t in seconds. Determine its position at the instant it changes direction. When I'm reading this problem I picture a parabola and the instant the particle changes direction...

I have a physics question that states: An amount of positive charge is distributed uniformly along the positive y-axis between y=o and y=a. A negative point charge -q lies on teh positive x=axis a distance r from the origin. Derive the x and y compontes of the force that the charge distribution...

Find the volume about the x axis: y=4x^2 2x+y=6 so, \sqrt{y/4}=x, x=6-y/2 I found the two graphs intersect at x=1, since there are two curves, which one should I use to find the height, I used x=(6-y)/2 to give me H=(-4-y)/2 and Circumference of (2pi)y All of this is giving me a...

in beam bending the resistance of a cross section is measure by moment of inertia about centroidal why. How do we know that the bends only about the centroidal axis . Any detailed discussion on this?

Ok, Not sure which forum this would fall under, so if it's the wrong one feel free to move it. I'm currently involved in a project that involved measuring acceleration from a 3 axis accelerometer using a PIC microcontroller. And I only have high school physics. :cry: I have 2 problems I...

I know that climate, seasonal and magnetic poles would be affected by this, but please, refer to them in your answer. What would happen if Earth were to suddenly reverse direction of its rotation, or suddenly change it's axis so it rotates side to side (like uranus) or front to back instead...

Hi all, I have a graph, plotted as Force vs. Time. Now, I want to plot the graph as Force vs. Distance. I'm taking distance = 1/2(F/mass)*(t^2). I think this is the right way to do it, but just need some confirmation. Thanks, Mike

Find the moment of inertia of a rod about an axis through its center if the mass per unit length is lambda = lambda (sub zero) time X. Answer (I = (1/8) M L^2) This problem is totally throwing me off. Normally lambda is equal to (M/L) so I am not sure what this new formula is doing to the...

http://physicsweb.org/articles/news/10/4/15/1?rss=2.0 "New Light on Giant Tilts" It's a major unsolved problem in planetary system dynamics. Anybody want to discuss?

How do I change the scale of the x-axis so that it does not automatically plot the number of data I graph but my customised x points? My situation: I like to graph hundreds of different points or data But only want the x-axis to be from 0 to 3, including decimals in between.

i keep getting nonzero off diagonal elements when i try to reduce to simple sum of squares, of the equation 2 x_{1}^{2}+2x_{2}^{2}+x_{3}^{2}+2x_{1}x_{3}+2x_{2}x_{3} what i have is \left(\begin{array}{ccc} x_{1} & x_{2} & x_{3} \end{array}\right) \left(\begin{array}{ccc} 2 & 1 & 0 \cr 1 &...

Does the moon rotate around it`s axis? for images see please: http://omega.webzdarma.cz/applety/moon/moon.html The moon doesn`t rotate around it`s axis, I think. In many books the moon does rotate around it`s axis. I have never undrestood why. Let mi introduce my point of wiew. We feel...

Sir, Why does a spinning top precess only when its axis is inclined to the vertical direction of the gravitational field?

The drawing shows the top view of two doors. The doors are uniform and identical. Door A rotates about an axis through its left edge, and door B rotates about an axis through the center. The same force is applied perpendicular to each door at its right edge, and the force remains perpendicular...

I have been having a debate that a vector in the positive x-direction must not have a y component other than 0. What are the other opinions on this wording and other possible wordings to mean that a vector is on the same line as an axis?

I'm searching for a theory that explains why the Earth is rotating on its axis and how long ago it began to do it. I should like to know, also, if rotation is common to all planets or there are some bodies that don't rotate. Are there any bodies that have their rotation axis parallel to their...

http://img334.imageshack.us/img334/6018/omg8gp.th.png Find the net torque about an axis through O I know Torque = F*r*sin(angle) but how the heck am I supposed to get the radius for that?

I know what the parallel axis theorem is, but I'm a little confused about when to use it. I recently had a problem where a hoop was rolling down an incline where I used the parallel axis theorem to find the translational acceleration and got it correct. However, I had a problem about a spool...

hey..i have a problem that states. a record has an angular speed of 34.6 rev/min. Find its Angular speed in rad/s. -so the answer is 3.623. The second part of the problem asks what angle, in radians, does it rotate in .717s. answers in rad. do you think you can help me? Also, i have...