Rotation Definition and 1000 Threads

When I googled it, I wasn't satisfied with the answers from various sites...some sites like universetoday.com gave me a glimpse but it was totally theoretical and based on assumption. Also I would like to know why some planets have retrograde rotation; what might have caused them to and why do...

Hello all, These days I am studying rotation and rolling of bodies. We know a body can be made to rotate about any point. Let's assume that an external force is acting on the rotating body fixed about the point of rotation, and this force made the body rotates faster that is its torque produces...

Homework Statement Will a maglev train beginning at rest slowly drift or accelerate due to the rotation of the earth? Homework EquationsThe Attempt at a Solution The Earth is a rotating reference frame, with points on the equator moving at approximately 1000 miles per hour. If the maglev is...

How can we calculate the rotation without seeing change of phase of object like in case of moon,we see the same phase of moon but how it can be rotating. So rotation without change of phase is possible if yes or no than how and why ?.

We all know we see only one part of moon means part which is facing towards earth But moon rotates also so we should able to see its other part(dark part) but we cant. I know rotational period of moon is equal to revolutionary period of moon but if moon is having rotational motion So we should...

High school student here I am designing an experiment to test the effect of temperature on the torque required to twist a piece of metal, and need some advice on where to start researching. What I need help with is A) finding a table of the torque required to twist steel when cold, and B)...

Homework Statement A rigid ring is fixed with three bearings evenly spaced around its circunference, which allow it to rotate but not to displace in the radial direction. An external force is applied in a fixed point P of the ring which moves with the ring. The bearings have friction. These...

If I push an object such as a cylinder of wood along a flat table (flat face of cylinder in contact with the table) through it's center of mass, the friction or energy required is not dependent of the surface area the block makes with the table, Friction = μ N, correct? And the energy required =...

Graphene's Hamiltonian contains first order derivatives (from the momentum operators) which aren't invariant under simple spatial rotations. So it initially appears to me that it isn't invariant under rotation. From reading around I see that we also have to perform a rotation on the Pauli...

For calculating a new "x" point of rotation I found the formula: x' = radius * cos(angle + -rotation) which converts to: x' = radius cos angle cos rotation - radius sin angle sin rotation Where does "radius sin angle sin rotation" come from? Jerry D.

I have a decent background in physics, but something that has always confused me is how to think about how the tension of the string in a tennis racquet affects how the ball leaves the strings. For example, the traditional lore in tennis is that tauter strings will give more control, whereas...

I have a rather odd question that delves outside of the realm of reality just a bit. Recently, I've had a bit of an obsession with designing ludicrous weapons. My current venture is a little bugger I call the 20MM Magnetic Accelerator Rotary Cannon. The MARC20 for short. It's an eight barreled...

Homework Statement Overhead view of a spring lying on a frictionless surface and attached to a pivot at its right end.The spring has a relaxed length of ##l_0=1.00m## and a negligible mass.A small 0.100 kg disk is attached to the free end at left.That disk is then gvena velocity...

Homework Statement Consider one rod of length L which is spun at its center perpendicular to its length; it will have a certain moment of inertia. Now, if the same rod is folded in the middle creating a certain angle and still spun at its center, what happens to its moment of inertia? Homework...

Homework Statement Show that every matrix A ∈ O(2, R) is of the form R(α) = cos α − sin α sin α cos α (this is the 2d rotation matrix -- I can't make it in matrix format) or JR(α). Interpret the maps x → R(α)x and x → JR(α)x for x ∈ R 2 Homework EquationsThe Attempt at a Solution So I know...

Homework Statement [/B] A flywheel with a D=1.2m is rotating at an angular speed of 200 rev/min (a) Whats the angular speed in rad/s ? (b)Whats v=? in the point on the rim ? (c)What const. ∝ ( in rev/min^2) will increase its angular speed to 1000 rev/min in 60 sec ? (d)How many...

Homework Statement A tangential force F acts at the top of a thin spherical shell of mass m and radius R. Find the acceleration of the shell if it rolls without slipping. Homework Equations Since the shell is rolling, friction does not act at the bottom. So equating the torque, F*R= I*α The...

Homework Statement A flywheel turns through 40 rev as it slows from an angular speed of 1.5 rad/s to a stop.Assuming a constant acceleration,find the tme for it to come to rest. Homework Equations ##w-w_0=∝t## The Attempt at a Solution In Δt secon the change in w...

I was watching a lecture and there was a connection drawn between classical rotational energy and quantum rotational excitation. The energy of a rotating system is $$E = (L^2) / 2 I $$ with L being the angular momentum and I the moment of Inertia. Then to make it quantum$$ n^2 * ħ^2$$ was...

Hello everybody, My question today is: Given a molecule that has an internal degree of liberty ( let's take the ethane molecule with its internal rotation as an example), how to write the kinetic energy operator by means of the corresponding internal coordinate? Thank you guys. Konte

Homework Statement A ball with radius ##r## is inside a hollow cylinder with radius ##r+R##. In the first part of the assignment, one has to calculate the minimum kinetic energy the ball has to have at the bottom in order to complete a full loop in the cylinder. It turns out to be...

This isn't a real homework problem (i.e. I made this problem up myself for my own purposes), but I figured this is the correct forum to post. 1. Homework Statement In the following figure we have two rods connected to each other, and the bottom rod is connected to the blue structure (G), and G...

Homework Statement I do not know if this is the right forum to be asking this, but it is the best i have found. A classmate of mine came with the statement that if the Earth stopped spinning we would all float off to space because the Earth's mass is to small to able to hold everyone down. I...

Homework Statement From the diagram below find the position of the man (##x##) if the system is in balance. Total length is ##L## and the man is distance ##x## from one end. Homework Equations 3. The Attempt at a Solution [/B] I know that the system must be in balance if all the torque and all...

Isaac Newton imagined a bucket of water suspended on a fine (ideally torsionless) rope, set spinning. Friction eventually causes the water to rotate along with the bucket. The surface develops a dip in the middle and rises at the edges owing to the water's inertia. (You see this effect every...

why force parallel to the axis of rotation do not make any torque.

Homework Statement In the first photo , i was told that the fixed end moment is zero when the far end is pinned or roller supported . Why in the example in the second and third photo( both end are fixed) , the angle is zero ? Homework EquationsThe Attempt at a Solution I think it's wrong ...

I need to start by saying that I'm not a physicist, nor a student of physics. I'm a translator, and my text is about rotations around the azimuthal nodal lines on the sphere. I need to find a name for a particular type of a rotation operator, which rotates the sphere around the x and y axes...

Homework Statement Three identical stars, each with mass m, form the verticies of an equilateral triangle with side length d and rotate in a circular orbit due to their mutual gravitation. What is the period τ of their rotation? I set up the FBD for each star and am now trying to figure out...

Homework Statement You have a space station in space far from any planets or stars in form of a hollow cylinder with inner radius R1 outer R2 length L and density Rho. On a symetric axis z are 2 astronauts, 1 at the middle and the second at distance H=2L from the center of the bottom of the...

http://imgur.com/a/8QjoW http://imgur.com/a/8QjoW Hello- I am trying to determine the dynamics of this linearly-damped hinge. Assuming that: v(0) = 0 damping constant = b door has mass = m I was able to determine that: ∑Fx = -Fd * cos(45-θ/2) + Rx = m*dvx/dt ΣFy = -Fd * sin(45-θ/2) - Fg +...

Homework Statement A uniform solid sphere of radius R, rolling without sliding on a horizontal surface with an angular velocity ωo, meets a rough inclined plane of inclination θ=60°. The sphere starts pure rolling up the plane with an angular velocity ω. Find the value of ω. Homework...

Homework Statement Two identical spheres A and B are kept on a smooth surface. They are given the same impulse I. The lines of action of impulses pass through the center of A and away from the center of B. Then: (A) linear kinetic energy of B will be less than that of A. (B) B will have...

Homework Statement A wheel of moment of inertia 5×10-3kg-m2 is making 20 rev/s. Find the torque required to stop it in 10s is (A) 2π×10-2Nm (B) 2π×102Nm (C) 4π×10-2Nm (D) 4π×102Nm Answer - (A). Homework Equations ω=2πƒ (ƒ=frequency) Power (P) = Γω. P = W/t. W = ΔK.E. = (1/2)Iω2. The...

Apologies on the vague title, I'm having some trouble describing what I'm trying to do and need some context. I have a 3D World Coordinate system that is static, using an extrinsic left-handed ZYX system. I have an object with a radius of 1 unit (generic), this is arbitrarily placed within the...

Hi I am confused about rotating magnet. Feynman lectures on physics 13–6 The relativity of magnetic and electric fields, http://www.feynmanlectures.caltech.edu/II_13.html , deals with two inertial frames. Wire is charged in some inertial frame. Can we apply it to tangential parts of curved...

I've written a space colony simulation game called High Frontier. It correctly simulates rotational stability when most of the mass is dominated by a single large spinning part. For example, a squat cylinder will be stable, but a long cylinder will end up tumbling end over end, as shown...

Homework Statement Spool made of two outer disks of radius R2 which are solid, uniform cylinders, which are connected by a massless inner cylinder of radius . Homework EquationsThe Attempt at a Solution I just have a quick question. If the mass is going down, the tension in the string would...

Dear Forum, I am filmmaker from Berlin and despite physics focus back in high school I am really bad at it. I am trying to get my head around some ideas I am working on and would kindly ask you for some tiny calculations. I hope this is OK and maybe even fun for someone here? So my questions...

1. Homework Statement : A rod of length l is vertically standing on a friction less surface. It is slightly disturbed from this position. Let w(omega) and alpha be the angular speed and angular acceleration of the rod, when it turns through an angle theta, then find the value of acceleration...

Suppose we have a rigid body that rotates around a point P other than its center of mass, with point P being a point of the rigid body. This implies that there are external forces to the rigid body. If the external forces cease to exist(like we have an axis passing through P and we suddenly...

I understand that the torque on a gyrating object is defined as the force vector cross multiplied by the lever arm position vector, which produces a resultant vector that is normal to both of the original vectors. However, when an object (let's say a disk) is rotating about an axis...

Homework Statement Show that a hollow cylinder of radius R_1, outer radius R_2, and mass M, is I=1/2M(R_1^2+R_2^2) if the rotation axis is through the center along the axis of symmetry. Homework Equations $$dm = \rho dV$$ $$dV = (2 \pi R)(dR)(h)$$ The Attempt at a Solution I was mainly...

Homework Statement A yo-yo consists of two cylinders with radius ##R##, mass ##M## and height ##H## connected by a smaller cylinder of radius ##r##, mass ##m## and height ##h##. Determine the yo-yo's acceleration in ##z##-direction, using its moment of inertia. Homework Equations Moment of...

Homework Statement How do I calculate the rotation velocity of a boomerang assuming that the period is like 0.5 seconds ? Considering a boomerang made of 3 rectangles, with an angle of 120 degrees between two of those rectangles... According to internet..we must consider a velocity of...

Homework Statement Two ice skaters of mass ##m = 50\,\mathrm{kg}## each are moving towards each other frictionless on parallel paths with a distance of ##3\,\mathrm{m}##. They both have a velocity of ##v_o=10\,\frac{\mathrm m}{\mathrm s}##. Skater 1 is holding a massless rod of length...

1. 2. Well, these are two pics on circular motion, i found on net... If the objects had a zero rotational motion before circular motion, and the next moment suddenly a force acts ( perpendicular to their linear momentum ) such that they move in circular motion,... which of these pictures...

Consider the eigenvectors ##(0, 1)## and ##(1, 0)## for the quantum system described the magnetic field ##\vec{B} = (0,0,B)##. Say I now rotate the magnetic field as ##\vec{B} = (B\sin\theta\cos\phi,B\sin\theta\sin\phi,B\cos\theta)##. Then the eigenvectors are supposed to change as...

Homework Statement [/B] The diagram shows a thin rod of uniform mass distribution pivoted about one end by a pin passing through that point. The mass of the rod is 0.380 kg and its length is 2.50 m. When the rod is released from its horizontal position, it swings down to the vertical position...

I appreciate the link to the field strength calculator. http://www.calctool.org/CALC/phys/electromagnetism/solenoid I'm also looking for recommendations on sources for magnets. What I'm trying to do is put together a Faraday Rotation Effect Lab. This is my Faraday Rotator, a 12 cm x 2.0 cm...