Axis Definition and 895 Threads

Torque is defined as: τ = rxF this means that the farther from the rotation axis of a body a force is applied, the more it will tend to rotate the body. My question is: Can anybody give me a simple argument that a force applied farther from the rotation axis should be better at...

Homework Statement A uniform sign is nailed into a wall at its top two corners. The nail on the upper-right corner breaks, and the sign begins to rotate about the remaining nail in the upper-left corner. The mass of the sign is 69 kg, L (length) = 1.6 m, H (height) = 2.2 m, and the moment of...

A 3-dimensional graph has infinite number of derivatives (in different directions) at a single point. I've learned how to find the partial derivative with respect to x and y, simply taking y and x to be constant respectively. But what do I do if I want to take the partial derivative with respect...

Homework Statement A uniform solid sphere has a moment of inertia I about an axis tangent to its surface. What is the moment of inertia of this sphere about an axis through its center? Homework Equations Ip = Icm + Md2 Isolid sphere = 2/5MR^2 The Attempt at a Solution This is...

Not sure if this is the right place to post it. Does anyone know how to plot negative axis upwards on Origin?

I can work out the acceleration of a block that will take along the plane when the axes are the ones along and perpendicular to the inclined plane. But, when I choose a horizontal and vertical axis I end up with the same mistake as this guy in this thread did...

Homework Statement Homework Equations The Attempt at a Solution So this isn't a specific question, I'm just having trouble with my definitions. In my book for f(x) = (x - 2) ((x + 1)^2) (x-4) it says that the zeros are at x = 2, -1, 4. On the page it shows that the graph doesn't cross the...

Homework Statement Hi I have a question - it is not homework, but something I have thought about for a long time. I really can't come up with a solution to the problem, and it is driving me crazy. Here is the problem: Say I have a linearly polarized monochromatic wave incident on an...

A vertically moving object projectile reaches a maximum height of 50 meters above its starting position What is the projectiles initial speed? What is the height above the starting point at 3.3 seconds?

Homework Statement Find the volume of the area bounded by y^2 = 4ax and x=a rotated around the x-axis. Homework Equations integral of pi R^2 dh The Attempt at a Solution I just don't know how to handle the x=a part of the boundary. Any hints? thanks

Note: The following are taken from Physics for Scientists and Engineers 6E http://img542.imageshack.us/img542/821/75796098.png http://img152.imageshack.us/img152/5615/70724407.png http://img804.imageshack.us/img804/6813/65815357.png I don't really understand why is that integral...

Homework Statement The area bounded by the x-axis and curve y = 4-x^2 is rotated about x-axis, find the volume.Homework Equations [integral] pi y^2 dxThe Attempt at a Solution the answer is supposed to be 512/15 pi

Homework Statement A uniform rod of length l is given an impulse at right angles to its length as shown. Find the distance of instantaneous centre of rotation from the centre of rod. Homework Equations The Attempt at a Solution Impulse=change in momentum or Impulse=mvCM (Am i...

Its stated that total energy of an isolated system is given by E = \frac{1}{2}mv^{2} + \frac{1}{2}Iω^{2} + mgh. Whats the correct form when the velocity is along 2 axis, that is, along x and y-axis like v = (2, 1)? Should the resultant be taken or just add the kinetic energies along each axis...

Sorry if i post this one in wrong thread, But can you help to solve this one? so i can review or study it by my own.. :D thanks!

Hello! I'm not sure this is the right place to ask, but i have a huge problem. I have an axis and it's origin, and also a point. I suposed that is enought to describe an ellipse, but how to do so? I want to describe it by having it's center and both it's radius. Some images to ilustrate what I...

I need to track Distance on one Axis with an Accelerometer for a rocket project (i know there are bettor ways t do this but i am dead set on this one) I was thinking as follows, Read Accelerometer Accelerometer*Δt=Δv Current speed+Δv=New speed distance+New speed*Δt=New distance

Hello, I'm trying to define an axis as a set of 3 unit vectors--u, v, and w. at a given point P Suppose we are given the following vector u. From this vector u, we must define a plane such that u is normal to the plane. This plane will be represented by two perpendicular vectors v and w...

Hi Please see the attached picture. It shows an atom, the filled black circle, which consists of a J=0 level (with m=0 sublevel) and J'=1 (with m' = +/- 1 sublevels). From the left is a nearly monochromatic laser impinging on the atom, which is linearly polarized along the same direction of...

Homework Statement Answers in the back of the book about x-axis= 190 about y-axis= 828Homework Equations Simpson's Rule: (dx/3)* sum of(sequence of coefficients {1,4,2...2,4,1}*sequence of function values{f(0), f(1), f(2)...f(n-2),f(n-1), f(n)}) Volume using Shells: 2π ∫ (radius)(height) dx...

All of you may have heard this. Without the Moon, Earth's axis would fly wildly out of control due to the other planets' gravity. Now, that makes sense, the Moon giving a stabilizing effect. But what confuses me is why Venus and Mercury both have near 0 degrees of tilt. They don't have a moon to...

Homework Statement A meter stick is held to a wall by a nail passing through the 60-cm mark. The meter stick is free to swing about this nail, without friction. If the meter stick is released from an initial horizontal position, what angular velocity will it attain when it swings through the...

I've been reading a few books on scattering of light from particles, in particular mie scattering of cylinders. At first I want to look at infinite cylinders, then finite cylinders once I understand a bit better. The problem is that all of the books I've looked at treat the problem where...

Hi there, first post on these forums. I have a seemingly simply question about beam bending. We (mechanical engineers) are all very familiar with the standard beam bending scenario. The beams are always shown being loaded perpendicular to the neutral axis, regardless of the type of support...

hey guys, I have a problem I need to solve for my masters thesis. I have an object that rotates in 3D space. There is no translation. Given that I have coordinates of one landmark at 2 instances of time I need to calculate axis of rotation and angle of rotation. is this sufficient...

Hi, how can i change x and y-axis scale to make sure that x and y-axis are on the same scale in matlab? my x-axis is from 0 80 but the y-axis is from -3 to 5, so in plot the axis are not the same but i want to have same scale on both axis. Thank you.

Hello, From what I've read, I understand that a spinning disc has a torque which resists the tilting of the disc's axis. From what I understand, the higher the angular velocity of the disc is, the more the disc will resist tilting. Can anyone tell me how to calculate this torque? If there is...

Hi, I would be happy if you could solve and explain following problem: Imagine some solid long object (wooden plank for example) being just like that in vacuum, free, without being fixed to any point of space. Then, imagine only one forse pushing this object in a certain point of object...

Why doesn't taking moments about an axis passing through point A or B work? Why must it be the center of mass here?

I am lost and confused. I have been on the same problem for 2 hours. I know all the formulas, but I'm not doing something right...

Homework Statement evaluate the integral: I_1 =\int_0^\infty \frac{dx}{x^2 + 1} by integrating around a semicircle in the upper half of the complex plane. Homework Equations The Attempt at a Solution first i exchange the real vaiable x with a complex variable z & factorize...

When i apply torque on a body, it will rotate around whcih axis? I guess its the axis along centre of mass but i don't know why? Also if the answer is centre of mass what will be the orientation of the axis- I mean there are infinite lines passing through a single point so which of those...

Homework Statement Find the moment of inertia of a uniform disk of mass m and radius r about an axis normal to the disk, through a point x from the centre. Homework Equations The Attempt at a Solution Let ρ be the density. I=ρ∫r^2 dA=ρ∫∫r^3 dr dθ in polar coordinates. However I...

Please consider http://gyazo.com/e5c5b4f7808a63e7e664440259ac3058 I agree with all notes made on that slide, but I don't actually get how they constructed the diagram from that? I understand that they line represents frequency so going to 0 to infinity means the line would travel from -0.5 to...

1. Problem I am attempting to model the dynamics of the system shown in the attached image. I have a DC Motor with two disks attached to it via springs and something similar to a servo horn. I have two questions. The first is how to determine the inertia of the disk and the spring about the...

Homework Statement y=x^2+1 X in (0,1) Homework Equations formula needed integral (PI [f(x)]^2 DX in the F(x) just plug in the equation right? The Attempt at a Solution took anti deritive of the original problem and came out with PI[1/3x^3+X]^2 my answer is 5.58 am i on...

Hi, I need some help, I have a system with 3 cylinders (I got the center of mass for the system). Now I need to calculate the moment of inertia for the system. I have tried to find some examples or general information, but they all show when the axis either is centered within the object or...

I have to draw cosine waves in relation to pattern formation for mathematical biology, for example, I have to plot things similar to these on the x-axis; cos( 2*pi*x / √5 ) from x= 0 to √5 cos( 3*pi*x / 2 √5 ) from x= 0 to 2√5 cos( 3*pi*x / 2 √(5/6) ) from x=0 to 2√5 And with the y-axis; cos(...

Homework Statement The curve x=y^(2) and the line x=4 is rotated about the x axis. Homework Equations pi* integral from a to b of Radius^(2) The Attempt at a Solution pi* integral from 0 to 4 of (square root of x)^(2) dx. My teacher has this answer as 8pi but I think that that...

Hello, I would like to know, how can I change units showed in axis. I would like to change those relative units (20000, 40000...) to μm. The conversional relation is 50 = 1μm, so instead 20000, 40000 i would like to have 400μm, 800μm. I enclose picture where it should be more clear what I am...

Homework Statement A circular loop in the XY plane of radius R and with current I moving in the counterclockwise direction. Compute B at (L,0,0) for L >> R0. Homework Equations Biot–Savart law dB= μ0I/4∏ *(dl X r)/r^2 The Attempt at a Solution I know that the B on the axis...

I recently read that the Earth's axial tilt fluctuates between 22 degrees and 24 degrees. Can someone explain what causes the tilt to change? If I assume the Earth is perfectly spherical, gravitational forces cannot change the tilt. So, is that the reason i.e. that the Earth is not perfectly...

I want to ask why a rod's rotational inertia with rotational axis at its end is not 1/2 mR2 but 1/3 mR2?

I was wondering if the angular momentum of anybody with constant \omega (angular velocity) about a point on the centre of the circular path and about any point on the axis of rotation is the same...

Homework Statement you have a +3C and a -1C charge on the x axis. the +3C charge is at the origin and the -1C is at x=1. At what point on the positive x-axis does E=0? Homework Equations E=kQ/r^2 The Attempt at a Solution So i have E=(-1k/r^2)+(3k/(1+r)^2) Setting E=0...

I was just wondering that when we have a molecule, and you introduce heat, the molecule starts to get translation, rotation and vibration energy. I'm considering just a molecule with two atoms and one axis which binds them together. Now the real question is that why is there only two axis in...

Homework Statement So here is the question: Matrix A corresponds to the linear transformation T obtained by first rotating a vector in R3 through angle ∏/3 about the z axis and then through angle ∏/4 about the x-axis. Find the parametric equation for the axis of rotation. Homework...

Hi, Concerning only the upper right quadrant of an ellipse... I know the distance from the center of the ellipse to the top of the ellipse, (semi-minor axis "b"), is 1000. I know the distance from the center of the ellipse to the side of the ellipse, (semi-major axis "a") is 1732. At the...

Hey guys, as the title says I can understand why the neutral axis does not pass through the centroid after reaching a point where the bending moment is max before the beam collapses. Say you have a straight structure supported by two double I-Beams and a weight in the middle. Why does the...

Hi I am studying Sports Science and researching the use of an accelerometer during specific wieght training type movements. I have a MEMS device (unfortunately I only have mininal details regarding it) which can measure upto 24G and 400Hz and comes with basic software that transfers the data...