Rotation Definition and 1000 Threads

Hi everyone, I've been working on this problem for a while now, and I was hoping someone here could point me in the right direction. Here goes: 1. Homework Statement A solid brass ball of mass 0.280 g will roll smoothly along a loop-the-loop track when released from rest along the straight...

Hello all, A bit of background. We are communicating with a microcontroller through a desktop computer. The desktop computer controls direction of rotation of the motor, and it can prompt a step in the motor causing a rotation. However, what can I do in terms of feedback? I have not taken...

I am having a bit of difficulty with the concept of unequal tension in a rope. What are the conditions for unequal tension? I read that the tension is the same when there is no acceleration. Why is this the case? Can someone explain this concept to me? Thanks :)

Homework Statement A torque acts on a wheel rotating at 19.8 rad/s and increases its angular speed to 23.5 rad/s in 11.2 s. Find the angle through which the wheel turns during this time. Homework Equations omega = theta/time The Attempt at a Solution 23.5 - 19.8/11.2 = .33rad/s/s --- this is...

Hi! I understand that if you have a stator with a a three phase electric signal going into it, both the frqyency and angular velocity of the magnetic field and the electric entry will be the same. Now when you feed it with 2 groups of three phases electric signals you get four poles, or at least...

1. The problem statement & given/known data A neutron star is a collection of neutrons bound together by their mutual gravitation. The density of such a star is comparable to that of an atomic nucleus (10^17 kg/m^3). a) Assuming the neutron star to be spherical in shape and of uniform mass...

Hi all, I'm looking for physical and mathematical explanations for a phenomenon I've noticed when working with rotated material properties relative to an XYZ coordinate system. For certain rotations (~40 to ~50 degrees) about a single axis the S12, S13, or S23 components of the compliance...

Hello, I am really struggling with calculating the final rotation of a spinning wheel. I am not even sure if my equation for changing the velocity of the spinning wheel given a coefficient of friction is even correct so I will post it here... change in angular velocity = angular velocity *...

How to derive the formula: v=wr where v is the tangential velocity, w is the rotational velocity, and r i the radius vector? From the attached image, it can be concluded that (each quantity is a vector): w=r x v, also v=w x r, and r= v x w. All three vectors are perpendicular to each other...

I don't have any background in any physics past high school, so I was wondering if someone could help me figure something out. I'm trying to build a robot that involves shooting off a foam bullet from a Nerf gun at different angles. I want to have a motor attached to the center of the gun...

I was reading on gyroscopes, and everything seemed to make sense: the spin angular momentum along the axis of the gyroscope changes due to the torque by gravity, causing precession. However, I can't understand why we are measuring angular momentum (the spin of the gyroscope) from the center of...

Whenever the car goes about a differential comes into action.This action generally starts with the spider gear starts to rotate about its axis,this causes increase in speed in one wheel and decrease in other.I want to how this spider gear starts to rotate about its axis what causes it to rotate ?

Hey guys, I'm trying to work through a question but the solution we have been given is extremely vague. I can't seem to figure out what any of the values such as Beta or Tmax are. If I knew how to work those two out, I'm sure I'd be fine from there... See attached image. Thanks in advance

Homework Statement The tumbler in an upright clothes dryer rotates at a critical angular velocity so that clothes passing over the top briefly experience weightlessness. If the radius of the drum is 0.30 m, what is this critical rotation rate? (Express your answer in both radians per second...

So let's say we have a neutron star. A neutron star is very massive and very dense therefore it has a very strong gravitational field. But also it is rotating very fast and it really hot. This means it has more energy than if it was stationary and cold. Of course if this neutron star has more...

Hi, I would like to ask you If you could help me with a (I guess quite simple) problem I have to solve. To put it into context: I want to program a helicopter for a videogame with a physical model. So the player controlls throttle, pitch, ... and the game calculates the correct response...

Homework Statement [PLAIN]http://i61.tinypic.com/10dwmtv. what is the instantaneous center of rotation for the rigid body. OA = 16 AB = 25 AD = 60 BC = 35 ωOA=2s-1 Homework Equations Vb=ωCB*BC The Attempt at a Solution I am assuming the values angles and vectors from red...

Homework Statement THe x and y axes have been rotated about the origin through a 45 degree angle to produce the X and Y axes.. Thus, a given point P (x,y) has coordinates in the first coordinate system and (X,Y) in the new coordinate system The orignal equation is y=10sech(x). What is...

Homework Statement 5x^3+10x^2+20x+15 is rotated through the angle 45 degrees to new xy coordinate system.Whats the equation to the coordinate system? Homework Equations The Attempt at a Solution New X= xcos(theta)+ycos(theta) New Y=-xsin(theta)+ycos(theta)

Hi there, right now I am making my first steps towards physics, and I would appreciate your help to solve some of my problems. As you surely have already noticed, I'm not english and I guarantee I'll make thousands of errors. Should I make any, please, try to always advise me, and if it's not...

Is it possible to generate energy from the Earth's rotation? Imagine a Foucault Pendulum attached to a dynamo shaft? http://www.google.com/patents/US8299636

I was wondering about how to speed up time because I was bored, so I considered rotating my body clockwise (in the northern hemisphere) in order to speed up the rotation of the Earth by creating angular momentum opposite to that of the earth. I was thinking that this would then speed up the...

Homework Statement A uniform bar of length 2l is rotated in a horizontal plane about its mid-point as center with an angular velocity ω. This case must be reduced to a problem in statics by the application of d'Alembert's principle, the "forces" acting being "centrifugal" forces. a) Plot...

I am working on this problem, they say if moments and products of inertia are computed with respect to the center of mass, the H(c)= -I(yz)ŵe(y) - I(xz)ŵe(x) + I(z)ŵe(z) how can I prove this?

For $a>0$, let $V$ be the volume created by revolving the region bounded by $y=b\sqrt{x}$ and $x=a$ around the axis $x=a$. The units of $x$, $y$, and $a$ are $[m]$. The units of $b$ are $[m^{1/2}]$. The value of $b$ remains fixed. For fun and practice, I did this question both with cylindrical...

Ok here is the question that is being asked. Note that I know how to solve it one way, but when I go about trying to solve this problem another way that I think should give the the same result, I don't end up with the same result. Question: A disk of mass M and radius R rotates at angular...

Homework Statement A group of American physicist works on a project where planar lines are in the form X=tP+sQ, where P and Q are two fixed different points and s, t are varying reals satisfying s+t=1. They need to know formulae for the images of the line X=tP+sQ in the following three cases...

Hi all! Supposed I have my solution of sucrose, my light source, my polarizer. I shine my light source on my polarizer and plane polarized light passes through my solution, how then do I measure the how much my solution has rotated my polarized light by? And also, what kind of container...

Homework Statement A 1 m long rod, 200g, is hinged at one end and held out horizontally, then released. What is the speed if the tip of the rod as it hits the wall?Homework Equations Initial energy = final energy rotational energy = .5Iω^{2} gravitational potential energy = mgh kinetic energy...

Homework Statement A mass m1 is connected by a light cord to a mass m2, which slides on a smooth surface. The pulley rotates about a friction less axle and has a moment of inertia I and radius R. Assuming the cord does not slip on the pulley, find (a) the acceleration of the two masses, (b)...

How can velocity uniformity in dynamos and motors be explained? What's the mechanism of that happening ? I'm aware that Newton's first law is involved in that situation where an equal and opposite torque must act on the coil during its rotation so the net torque is Zero and the coil keeps...

Hello All, A curious person here would like to know if a planet gains gravitational force as it rotates around the center of its galaxy. From what I understand this speed is quite impressive (the speed at which we travel around the center of our galaxy) so I'm wondering if the sheer mass of...

If you rotate your rectangular coordinate system (x,y) so that the rotated x'-axis is parallel to a vector (a,b), in terms of the (x,y) why is it given by x'=ax+by y'=bx-ay I got x'=ay-bx, y'=by+ax from y=(b/a)x. By the way this is from solving the PDE aux+buy=0 by making one of the...

EDIT: Okay now that the admin has cleaned up my mess, please scroll down to see the correct image and the question on the 3rd post in this thread.

Homework Statement A have two points 60,892857 12,496875 -4,837500 70,714286 14,915625 -5,240625 I have to rotate for -0,067195795 radians. Homework Equations ##\begin{bmatrix} {x}'\\ {y}' \end{bmatrix}=\begin{bmatrix} cos\alpha & -sin\alpha \\ sin\alpha & cos\alpha...

Hi all. It is well known that in Schwarzschild space-time, a torque-free gyroscope in circular orbit at any permissible angular velocity at the photon radius (also known as the photon sphere i.e. ##r = 3M##) will, if initially tangent to the circle, remain tangent to the circle everywhere along...

Hi All, I am trying to determine the correct equations to apply with a problem I have run into at work. Basically I have a shaft with a cutter with straight flutes, I am trying to find out the torque load on the shaft when the cutter flutes make contact with the material they are cutting...

I need some clarification here. We know that the Earth rotates about it's own axis and also around the Sun. Now my questions are: 1. In the geocentric model of Ptolemy the Earth was at the center of a circle while the planets (and sun) moved along epicycles and the centers of those epicycles...

Hi All, I have always been haunted by this basic question and will be grateful to anyone who can shed light on this! Please consider this experiment - A cube is kept on a plane horizontal surface on the equator (where the Earth's rotational speed is the maximum). If the friction between...

Hello everyone! If a ball is released from the top of a very tall building, would it land ahead in the direction Earth is rotating (to the east) or would it lag behind i.e the Earth "moves out" from underneath it so it lands to the west? I think it should land ahead to the east since its...

I have been reading about rotation curves, and the I understand the basics, but I am trying to understand the basis / meaning of the curves? Are the findings based on redshifts of individual stars / "bins of light" at set distances from the centre of the galaxy? And given that the...

Hello, First time posting to Physics Forums. I have been thinking about rotation transformations and am a bit confused on how trig works in 3D. In 2D, convention says the positive x-axis points to the right, the positive y-axis points upward, and positive angles are measured from the...

Homework Statement In rotations of diatomic molecules such as HCL, the hamiltonian is found to be: \hat H = \frac{\hat L^2}{2\mu a^2} where ##\mu## is the reduced mass, a is the separation. (a) Find the energy levels and separation. (b) Explain why rotational spectra of HCl...

A interesting question came up to my mind, and it's related to the concept of different synchonization methods. If we change the synchronization parameter from 1/2 to some other value, light will have different velocities in opposite directions, which implies that two velocities with opposite...

I'm struggling to get my head around tidal acceleration. I get what is IS, I know how to calculate it, but what I'm not sure is how to apply it in a way that's meaningful to me. So. If we took a stationary Earth (i.e. non rotating, tide-locked) and have the moon magically appear in orbit and...

Hi, My textbook does not really go into the details of rotation about a bond. I know single bonds can rotate easily. What about double bonds and triple bonds? The pi bonds would be broken. Does that mean new compounds are formed? My textbook says rotation around triple bonds is easy...

If a fast moving and heavy object strikes earth,can it change its spin or rotation or both?

Could someone explain how angular velocity points perpendicular to the plane of rotation? I mean what is a physical explanation of this? (not mathematical) I mean for a rotating object it's easy to see that is has a tangential velocity that always points tangential to the direction of...

I was doing a question in Taylor book (example 3.3) where a sticky putty is thrown at a stationary wheel. To solve it we use conservation of angular momentum. What I am confused about is that the wheel is initially at rest and has no angular momentum initially. But when the putty is thrown at it...

calculate the volume obtained when the area bounded by y=e^x, x=1, y=1, is rotated around x=4. use shell method. Can I see your integral? My teacher gave me the first integral. I found the second one here: BUT: the two do not give the same numerical result: integral of pi((4-lnx)^2-9) FROM 1...