What is Rotate: Definition and 244 Discussions

A rotation is a circular movement of an object around a center (or point) of rotation. The geometric plane along which the rotation occurs is called the rotation plane, and the imaginary line extending from the center and perpendicular to the rotation plane is called the rotation axis ( AK-seez). A three-dimensional object can always be rotated about an infinite number of rotation axes.
If the rotation axis passes internally through the body's own center of mass, then the body is said to be autorotating or spinning, and the surface intersection of the axis can be called a pole. A rotation around a completely external axis, e.g. the planet Earth around the Sun, is called revolving or orbiting, typically when it is produced by gravity, and the ends of the rotation axis can be called the orbital poles.

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  1. J

    Flip vs. Rotate: Which is Spinning an Object 360º?

    Hello, Is spinning an object 360º horizontally a flip or a rotation? This is not homework, this is work work. -Chris
  2. ravinaval

    Torque required to rotate this wheel?

    Dear experts, I am an electrOnics engg and weak in mech parts . please refer to the attached images of this hand machine, The wheel at the top weighs 30 kg and is rotated through hand because of which the horizontal plate attached at the bottom moves down and cuts objects using die placed. I...
  3. B

    Torque needed to rotate low-speed shaft

    Hi, I'm interested in wind power/energy and I would like to know how much torque is required to rotate a low-speed shaft of either a 2mw or 3mw wind turbine at an rpm of 20. Also, I'd like to know if the weight of components (e.g. the shafts, gears, or any other components) affect how much...
  4. C

    To find power to be used to rotate a circular disk

    A circular disc of 10 feet radius has to carry load 5 tonnes and it has to rotate very slowly say .. 1 rpm. how much power hp motor should be used? Can Anybody help me with thie.. Man thanks in advance...
  5. M

    Deriving Photon Rotation Formula for Monte Carlo Simulation - Step-by-Step Guide

    Hello and apologies if the title of the question is not very precise. Question: I am reading the document talking about the simulation of photons in tissues using a Monte Carlo simulation. The exact title is "MCNP - A general Monte Carlo N-Partcle Transport Code". Link to MCNP - A general...
  6. H

    Rotate object in space to direction [Simulation]

    1. Homework Statement ----------------------------------------------------------------------------------------- CONTEXT: I'm writing an AI simulation for am upcoming assessment in my computer programming course, and I'm having some trouble with the physics and calculations. The simulation...
  7. R

    Torque required to rotate steel pipe on rollers

    Hello, I'm stuck on what should be a fairly simple problem. Trying to calculate the size of motor required to rotate steel pipe at 0.33RPM around its axis, on 2 sets of rollers, 4 wheels total (hard rubber). Pipe 48" OD Mild Steel pipe 0.5WT 24m in Length Rollers 4 x 12" Rubber...
  8. D

    How do you rotate an electron 360 degrees?

    I went through an undergraduate physics program and I've internalized the results of the Stern–Gerlach experiment to the point where it makes more sense to me than the classical version. However, one thing I somehow missed (or maybe it wasn't taught) is what "must rotate an electron 720...
  9. B

    How many gears to rotate a 34mm dial 28.07 degrees?

    Okay, I am no math genius here, so this may sound like a stupid question, but I am curious to know, how do I find how many teeth a gear will need and how big or small it should be to rotate a 34mm dial 28.07 degrees? Cheers
  10. I

    Required force to rotate the Engine piston

    Dears, please help me: How to Calculate the Required Force to Push the Car Engine Piston Down if I Want to Rotate my shaft in 1500rpm, My Piston Dia Is 50mm, Piston Hight Is 100mm, Piston Mass Is 1kg, My Engine Is 4cylender and 4stroke? regards ibrahim
  11. G

    Why Objects Rotate: Rigidity, KE & Magnets

    Just from the most basic concepts, is it due because of rigidity that when a force is applied to a non COM point that an object rotates? Why does the magnitude of rotation increase with increased perpendicular distance from the pivot or COM point. Also do you transfer more KE to an object...
  12. E

    Rotate Point in Matlab Plotting

    Homework Statement i need to fix a point and rotate another one Homework Equations The Attempt at a Solution i did this i've created this: x=rand(1,3) y=rand(1,3) scatter(x,y) how do i select and make one point fix and make the other point rotate around it?
  13. I

    Required torque to rotate a solid cylinder around its axis.

    I'm a mechanical engineer and I am more specialized in structural calculations than dynamic calculations and now I'm faced with a basic dynamic problem and would need some help. I have a solid cylinder (shaft) that I want to rotate around its axis. The cylinder is supported by two bearings at...
  14. E

    How fast can a particle rotate?

    Without moving in any direction, what is the maximum speed at which a particle can rotate? Does it depend on its mass or size? Is there a maximum speed of rotation analogous to or dependent on the speed of light? If so, are there any odd temporal effects from the perspective of the particle...
  15. G

    Bell experiment: Rotate measurement device 180°

    Hi, I was just writing another thread when I stumbled upon something strange: What if I now make a slight change and replace ##\bf{b}\rightarrow-\bf{b}##? The expectation values containing ##\bf{b}## change signs and I get $$\left|\frac{1}{\sqrt{2}}-0\right|=\frac{1}{\sqrt{2}}\leq...
  16. L

    How to rotate Cartesian coordinate system?

    Hello, I would like to rotate the Cartesian coordinate system ( i=(1,0,0); j=(0,1,0); k=(0,0,1) ) so that angles between new and the old axes be equal to α, β and γ, respectively. Is any simple way similar to the Euler transformations to accomplish that?
  17. 7

    What happens when we rotate crystal while shooting electrons at it?

    I know that if we shoot narrow beam of electrons at the crystal (we don't change the angle) we will get a diffraction of electrons according to the brag's law. Therefore we get minimums and maximums on the screen around the crystal. Until now we have been dealing with problems where...
  18. N

    How do I rotate a linear function around the z-axis?

    Homework Statement I have two coordinate system (x, y), (x', y') that differ by a rotation around the z-axis by an angle \alpha. In the coordinate system (x', y') I have a function f(x', y') = C, where C is a constant. I would like to express f in the coordinate system (x,y), where it is a...
  19. B

    Will this rotate like a Foucult's pendulum ? Why not ?

    Hi A Foucault's pendulum consist's of a heavy weight at the end of a long string with the string so suspended that it allows movement in any plane (eg. a string supported from a bearing fixed to the ceiling). The plane of the pendulum then rotates opposite to that of the Earth thus at the rate...
  20. mesa

    Does a charged particle rotate when traveling through a static Bf?

    I have been looking at mass spectrometers, in particular the interactions between the Bf ind of a charged particle in motion in a static Bf of the spectrometer. Figure 1 and 2 shown below are a basic 2 dimensional slice of the problem from the top (fig 1) and from the inside of the radius...
  21. M

    NMR - does rf cause transitions or simply rotate the magn vector?

    Am I wrong in thinking that the rf radiation used in nmr is not "absorbed" by protons to cause transitions between spin states but rather it is only there to provide a magnetic field which can rotate the magnetisation vector away from the primary field?
  22. A

    Will the ball rotate on a frictionless slope?

    There is a ball placed on a frictionless slope. As we all know that, since there is no friction, the ball will not rotate. But after drawing a free-body-diagram and decomposing the gravity, we find that the net force mgsinθ has a torque relative to the contacting point with the value of mgsinθR...
  23. H

    What is the axis of rotation for a freely moving rigid body after a collision?

    hi. I have an essential question. Suppose we have an complex shape at complete rest freely in space. There exist no forces at all. If we collide it in a point, at which axis it will be rotate? How I find it? I want the answer be in general and for all shapes.
  24. M

    Can a Lift and Rotate Mechanism Handle Heavy Duty Machining Needs?

    Hi all I need a bit of inspiration for a new CNC machining Fixture design. First the top of the fixture must be raised to get free of the guide pins, and then the top must rotate 120 degrees before it must be lowered over the guide pin again. I was looking for something like a rotary CNC...
  25. J

    Statics, determine the force required to rotate a body

    Homework Statement I´ll use a picture to show the problem: Homework Equations Sum forces=0 Sum Moments=0The Attempt at a Solution Basically I´m not sure about the forces on the free body diagram and I´d like to talk about them. Assuming that P is not acting, and the body is masless...
  26. S

    What Torque is Needed to Rotate a Solid Bored Ball?

    I want to calculate the torque required to rotate a ball. 1. Ball is solid having mass M kg. 2. Ball is bored through about its axis. 3. Ball is rotating about the axis XX Please see attached file.
  27. S

    Torque required to rotate a circular sector inside a drum

    What I have ? Have a 16’ x 72’ rotating drum There is a solid circular sector inside the drum What I need ? Want to Calculate the torque required to move that solid circular sector from the intial position to the position shown in attached picture (90 Degrees rotation) Data ...
  28. R

    Why do pistons rotate in only one direction?

    Why is it that pistons always, say rotate clockwise, and not counterclockwise? Is there some sort of imbalance on the piston that causes it to only move in one direction?
  29. N

    Rotate the wheel to a specific point

    In this wheel we have 6 pieces. The top of the wheel is the specific point. The specific point gives information of pieces. Now it gives information of the blue piece. So if i click on one of the piece for example purple, i need that purple piece to goes to the specific point and automatically...
  30. 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 =...
  31. I

    Why rotate Beukers's 0th integral to calculate zeta(2)?

    While reviewing calculus, I noticed that James Stewart's Calculus 3rd ed., chap 14, problems plus (at the end of the chapter), p.965, prob#2 asks the student to show that \zeta(2)=\sum_{i=1}^\infty\frac 1{i^2}=\int_0^1 dx\int_0^1 dy\frac1{1-xy}=I_\circ by rotating the integration region by...
  32. S

    Rotate 1 plane in 3d space to be parallel to another

    I'm not sure if this is the right forum. I'm actually trying to solve this for a computer program given shape A and shape B i'd like to rotate shape A so a given face is parallel to the nearest face of shape B http://postimage.org/image/shb6kyv6d/ attached image but i can't see it...
  33. P

    How did gravity build astronomical objects that rotate?

    How did gravity build astronomical objects that rotate? It seems to me a safe bet, supported in part by observation, that the heterogeneous assembly of known astronomical objects comprising the observed universe, whose contents range from minor planets (one named for my mother) to the recently...
  34. T

    Why optically active molecules rotate light?

    Say, we have a solution of pure form of R-alanine. Say, the molecule has it's COOH group directed along positive y-axis and rotates the z-polarized light clockwise - the question is why the same molecule with it's COOH group in negative y direction won't do the opposite.
  35. S

    Force required to rotate spindle.

    I am working on a six sigma project to reduce endbreaks in Beaming (textile). I am trying to find a device to measure the force required to rotate a spindle. There are 1000 spindles that hold packages that are transferred to a beam. Each spindle has a wooden brake that applies a force to the...
  36. H

    How To Rotate a Small Cylinder using D.C Motor

    Okay I hope i can get some quick replies , its urgent i have a science project coming and what i want to do is rotate a cylinder using a d.c motor its a relatively small cylinder radius = 4 cm length around = 15 cm mass will be around 200-300 grams now i can't figure out how can a small...
  37. H

    Why do we rotate along with the earth?

    Do we rotate along with it because of it's gravitational pull? Or is it friction?
  38. R

    Using a motorbike engine to rotate a generator

    Hi, I am thinking to use a 100c 8hp motorbike engine to rotate a 2KW generator which must be turned at 1500rpm. I thought of setting the bike engine to 2200rpm on no load so that when I put the generator on full load, the rpm hopefully will not go under 1500rpm. So what I want to know is, if...
  39. R

    How can I rotate a parabola.

    How can I "rotate" a parabola. I want to take an image and make it kind of wavy to distort it (like in a capcha form the letters are distorted sometimes with a wave) . So i figure that I could translate the pixels along a parabola. So the function where y=X^{2} would make the image curve...
  40. J

    Rotate a cylinder to allign axis

    Hi i have cylinder geometry . bottom (cross section)circle centre point is x1, y1, z1 and top is x2, yz, z2. cylinder centre axis is not allign with any (Global x,y,z) axis. if i want to align a cylinder with Global axis(x,y,z), what is angle need to rotated with respect to x ,y ,z (Global )axis.
  41. G

    Does a floating object always rotate about its centre of mass?

    If a large, stable floating object is placed in the ocean, free floating, and the tides and currents act on that object causing it to rotate, will it always rotate about its center of mass?
  42. A

    Understanding Why a Rod Doesn't Rotate Around Its Center of Mass

    Consider a free rod lying horizontically in the air. Gravity produces no torque around the center of mass. Now let the rod be attached to a hinge like of that one the picture. Now the hinge provides an upwards force on the left end of the rod, whilst there is a torque effectively acting at the...
  43. G

    Determine Origin to Rotate Vector B to Equal A

    Given two 2D unit vectors (A and B) in different directions and positions in the same horizontal plane, is it possible to determine the origin (point of rotation) required to make vector B = vector A (same position and direction)? All this assuming that vector B is a rotated (only) version of...
  44. N

    Determining Dipole Rotation: Clockwise vs Counterclockwise

    This is not a homework question I encountered this while revisiting the Electric Dipoles . First of all if someone explains me why the dipole So in the image above which way should the dipole rotate ? Anti Clock Wise or Clock Wise . What My intuition says is the Energy of a dipole is U...
  45. A

    Particle-Rod Collision: Rotation or Translation?

    A particle hits a rod at one of its end in space. Now will the rod rotate or translate or do both...What part of the force goes into translation/rotation ?? If the above scenario happens in air, what will differ?
  46. A

    Torque required to rotate a hollow cylinder

    First let me start off by saying I was a liberal arts major so I need some help with some formulas I've researched. I'm rotating a hollow cylinder that is 8ft in dia. x 8 ft long. The cylinder weighs 3750 lbs and will be filled with 20,093 lbs of watered sewage sludge. Total weight = 23,843lbs...
  47. L

    Do objects within a galaxy rotate in the same direction as the galxy itself?

    Hi, I have been trying to understand the nature of rotating objects within a galaxy, but with limited sucess. I am trying to understand if the rotation of objects (for example solar systems / stars / black holes within the Milkyway galaxy) are generally consistent with the rotation of the galaxy...
  48. L

    How to rotate a 3D complex vector?

    Hello, I have a 3D complex vector k=[k1,k2,k3], and k1, k2, k3 are complex numbers respectively. Now, I want to rotate k to a new vector t=[1 0 0]. However, I do not know the mathematical expression of rotation matrix. What is the difference between rotation in real domain and rotation in...
  49. J

    Why and how chiral molecules rotate plane of polarisation?

    I have been studying stereochemistry and it says that optically active molecules(chiral molecules) rotate plane of polarisation. I suppose that's because of the electrons in the molecule. I know that all molecules can rotate the plane of polarisation but when achiral moelcules are present in...
  50. C

    Torque required to rotate a disk

    Homework Statement How much torque is required to rotate a disk or diameter 1.4cm, height 1cm, weight 12g? Homework Equations I think Iz = mr^2/2 Torque = force x distance The Attempt at a Solution Iz = 2.95 * 10^-7 I do not know where to go from here. Thank you.
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