Rotate Definition and 238 Threads

I just read that the reason molecules rotate plane polarized light is because the light interacts with the electron cloud of the molecule. That makes sense but why aren't achiral molecules optically active? Achiral molecules have electron clouds too so why don't their electron clouds cause...

Homework Statement Homework Equations I_solidcylinder = .5mr^2 I_thinring = mr^2 torque = I*Ω (where Ω = angular acceleration) change in theta = .5(Ω)(time^2) The Attempt at a Solution Attempted to solve for angular acceleration: (2.5)(9.8)(0.1) = (3*0.25^2 + 0.5*4*0.1^2)Ω...

Okay, a few days ago I posted a question about torque, and recevied A LOT of useful help on understanding the term. I however must admit, that I still don't quite have the intuition behind why a greater torque causes an object to rotate faster. THEREFORE: Can someone with logical, physical...

Homework Statement The Hubble Space Telescope is stabilized to within an angle of about 2 millionths of a degree by means of a series of gyroscopes that spin at 1.92×104 . Although the structure of these gyroscopes is actually quite complex, we can model each of the gyroscopes as a thin-walled...

LEASE HELP! -Add an axis to current rectangle -Draw both piece of arm -rotate object first axis 20 degree --redraw. -then, rotate 2nd part about 2nd axis to -30degree my current code for rectangle is %RECTANGLE('Position', [x y w h]) w=4.5; %width h=.5; %height x=1.75;y=2.75...

When phasors are used,for example to illustrate some of the properties of waves,all of the texts seem to emphasise that the phasor rotates anticlockwise.Why anticlockwise?I have always assumed that the direction is just a convention...or am I missing something?If it is a convention then does...

There are two representations of black holes that I see in the popular media. Could you help me find the answer to a (or two) question about this please? 1. Feeding black hole with an accretion disk - I assume that the accretion disk is a product / consequence of rotation (in addition to the...

Homework Statement A vertical cylinder is sitting against a wall. It has a weight of 20N and no given radius. A force is applied tangentially in a vertical direction on the side not against the wall. The coefficient of friction is 0.499 for all surfaces. What is the maximum force so that...

Homework Statement Consider a long wire running in the vertical direction with a rectangular loop of wire beside it as shown. Now suppose that a constant current, I, flows upward along the long wire, and the same magnitude current, I, flows clockwise in the loop. As viewed from the top...

Hi, I was watching http://video.google.com/videoplay?docid=-2622437302869951111" the other day and he described photons by an 'amplitude' which actually means a complex number, which rotates over time. This rotation speed gives the photon's colour/energy/frequency. Then later in the lecture...

I am looking for a type of motor that can rotate gears and a large object and only rotate once every 12 hrs. I am having a hard time located one.

Can anyone help me out in calculating the power required to rotate a Horizontal Kiln resting on Rollers of following data: Kiln Mass 60000 kg Kiln Length 35 m Kiln Diameter 2.8 m Roller Diameter 0.8 m Radial distance between two centers 1.992m Kiln...

can someone help me?.. i have 5000kg suspended load..how do i calculate the force needed to rotate this load 90 deg. assuming perfect bearing?..thanks

Will a free falling rod rotate ? When we consider a bicycle is turning on a flat plane, we know that there is friction, which provide centripetal force on the bicycle. And we know that the bicycle is no longer perpendicular to the flat plane so as to reach equilibrium. What I want to ask why we...

I'm sorry for posting another thread but I'm totally lost here.. Homework Statement A wheel and axle having a totel moment of inertia of 0.002kgm is caused to rotate about a horizontal axis by means of an 800g mass attached to a cord wrapped around the axle. The radius of the axle is 2cm...

Hi all, I am new here as i want to ask something about an engineering project i am working on. I need a motor to rotate a 200 grams cylinder which will be hanging from the motor's shaft (vertically). I wanted less than 100 rpm so the motor I chose is a 2.1W 6V DC motor with a 50:1 reductor...

Homework Statement Rotate the area bound by the following lines around the x-axis. y = x^2+1, y = -x^2+2x+5, x = 0, x = 3 Homework Equations None that are uniform enough to put here considering I'm fairly sure it's not washer... The Attempt at a Solution

Let a clock A be at rest in an inertial frame and let a clock B rotate around it with constant velocity and constant distance from A. Let v be the velocity of B relative to the inertial frame. Both clocks count how long it takes for B to rotate once. According to clock A, the time it takes is...

Let's say I apply a horizontal force on an object sitting on a table. So there's friction. I know how to determine whether it will move or not-- I just see whether the applied force is bigger than the friction force. F > Fs there's movement Fs < F there's no movement That I know. But what...

Hi, I'm working on an engineering project and I need to get a 30pound base to rotate at speeds between 6 rotations per hour and possibly 1 rotation per hour. Does anyone know where to get such a motor, or if it is even possible? Can anyone think of a better more efficient way of doing this...

I am doing a project about the earth, the sun, and the moon. My question is why does the moon rotate around the earth?

I done this calculation But something wrong. cylinder weight: 17000 lb weight , Diameter = 36"= 3 ft, length = 5 ft. , 3000 rpm , time=90 sec. Aceee = Change in angular velocity / time Angular velocity = 2xPi (3.14) 3000/60 = 314rad / sec acee = ( 314-0) / 90...

Homework Statement This is a two part problem, but I don't know what equation to use for part II. a) A record has an angular speed of 15.4 rev/min. What is its angular speed? Answer in units of rad/s. 1.61 rad/s b) Through what angle does it rotate in 1.1 s? Answer in units of rad...

Homework Statement A 3.20 kg block is attached to a string that is wrapped around a 1.17 kg, 4.08 cm diameter hollow cylinder that is free to rotate on an axel through the center. The block is released 1.09 m above the ground. What is the speed of the block as it hits the ground...

I've been trying to solve one of my MATLAB problems for about 2 weeks now and I am completely lost as to how to solve it. It seems like it would be rather easy to do, but I cannot figure it out. I have referenced our Calculus 2 textbook, MATLAB textbook, and Google but I'm still stuck. The...

NOTE: BEFORE YOU RESPOND PLEASE KNOW THIS IS AN ASSIGNMENT QUESTION (worth 1/6 % of total subject) AND AS SUCH I DO NOT WANT AN ANSWER TO BE GIVEN TO THIS PROBLEM. I have tried this question many times in different ways and unfortunately I am unable to get any of these multiple choice answers...

Everyone affirms that a circularly polarized plane wave has no angular momentum, though it contains density of spin. However, a circularly polarized beam of any big diameter has spin angular momentum, which is localized at the surface of the beam, though the spin is allocated in the interior of...

Why do things rotate? I know what torques are...the question is deeper than that... This is not any homework or coursework problem. This question has been troubling me since it first popped into my head. Suppose there are two point masses both of mass m, connected to each other by a massless...

Does the ball rotate about its axis?! Hi Newbie here, I have a disagreement with an associate. I say that a ball on a string moving in a horizontal circular path rotates about an axis perpendicular to the said circle. He insists that it doesn't as it would wind up the string if it did...

is it possible for a body to rotate on its centre of gravity

Hello mathematicians, I'm creating a program and I need in this program to rotate some planes around the origin, while I'm given the coefficients a,b,c and d for this plane, they represent a plane of the form: a x + b y + c z = d So these coefficients are given and I want to rotate the...

I know that the Earth rotates around the sun, but what does our solar system rotate around? P.S. I'm a noob when it comes to anything related to astronomy, sorry.

can any celestal body or anything rotate at speed of 90 degree per second with a radius of of more than or equal to 3 X 10 ^ 8 metre ? is it possible?

A block of mass m is on a frictionless inclined plane with no initial speed. The net force which equals to the component of the block's weight along the inclined plane, acted through the block's centre of mass, so there is no torque acted on the block, so the block does not rotate and just...

Hi guys, was doing some thinking on torque, we all know that we can calculate torque by using T= Force x radius. But let's say if i have a cylinder of mass x kg which has a radius of r, sitting vertically on the floor (flat surface on the floor). How do i determine how much torque is required to...

Can anyone recommend a textbook or web paper that proves that, in general, a free rigid body will act in the following way when the body is subjected to a force (or impulse) that is torque producing: a) The center of mass (CM) moves in a straight line. b) The body rotates about an axis through...

Hello :) Does an artificial satellite rotate in its own axis? tia

Hi All, Cable drum, OD-50" weight abt 3 ton.. support by shaft horizontally.Both end of shaft is mounted on bearing. now i need to select electrical motor to rotate the this drum. drum need to rotate constant 30 rpm speed.. please some one help to calculate the power required to rotate.

In the beginning scene of the film One Eight Seven, Samuel Jackson's character has one of his students hold a bicycle while sitting in a chair, and pump the pedals until the wheel got up to around 180 rpm. When he told the student to tilt the bike to the right, the chair started rotating...

When a ball rolls down an incline without slipping friction causes the ball to rotate CCW When a ball with an initial velocity climbs up an incline friction is now in the opposite direction as in the previous case, the problem now is which force causes the ball to rotate CW. It can't be...

I want to calculate the torque of the construction or the needed Power (Watt) to rotate it. The construction is a tube and on top of tube is stuck a rectangular parallelepiped: Tube: inner diameter=d=92mm, outter diameter=D=102mm, lenght=L=3000mm, mass=12.34kg Rectangular...

The title states it all.

does the Earth rotate and undergo revolution with the same speed?is the rotation and revolution in same direction

How do you calculate amount of power needed to slowly rotate shaft under bending moment? This is not related to transmittal of torque. Given: shaft size span between support bearings bending moment value rpm Assume: slow rotation (ignore centrifugal forces caused by deflection)

[b]1. Homework Statement Calculate the time the moon rotates once around the earth, and show that you have to add 4 hours to that since the moon & the Earth rotate around their center of mass. hint: use the reduced mass: \overline{m}=\frac{m_{1}m_{2}}{m_{1}+m_{2}} mass of moon...

Homework Statement The maximum indicued emf in a generator is 205rpm is 43.0V. How fast must the rotor of the generator rotate if it's to generate a maximum inducded emf of 55.0V? Homework Equations E= NBAsinwt The Attempt at a Solution 205r/m*2 (Pi)/ 1rev81min/60s = 21.46rad/s magnet...

how gravity make planet to rotate? If you asked anybody why things rotate;they will answer you if you mean in astronomy the reson is gravity and if you mean at the level of atom the resone is electracal force but that is not what i want . i want to know how gravity do this and what really it...

Hi, I was researching the force required to spin a space ship. There is an old thread here but I'm not quite understanding the post. https://www.physicsforums.com/archive/index.php/t-151000.html To move a spaceship forward we have something like F = ma. 1000 kilogram space ship...

This is another thing that I have trouble figuring out. Why do the spokes on a wagon seam to rotate backwards at certin speeds? Help!

Hi, I am stuck on what should be a fairly simple problem. I need to calculate the torque required to rotate a pipe weighing 30 lbs resting on bearings at constant speed. How should my approach be? Do I need to actually measure the torque required using a sensor? Thanks, Mike