Axis Definition and 928 Threads

... so that there are no seasons and it's spring forever? It would make many species go extinct. But is it possibly a good thing in the longer term? Imagine it's summer forever, like in Equador. Or spring forever, like in a flower conservatory. Is there anything wrong with this...

Homework Statement What angle is between function y=\sqrt{3}x and Ox axis? Homework Equations For example is logicaly clear that angle between function y=x is 45 degrees or \frac{\pi}{4} The Attempt at a Solution I just know that answer is \frac{\pi}{3}, but can't understand how...

Homework Statement Prove that on the axis of any parabola y^2 = 4ax there is a certain point K which has the property that,if a chord PQ of the parabola be drawn through it ,then \frac{1}{PK^2} + \frac{1}{QK^2} is same for all positions of the chord.Find aslo the coordinates of the point K...

Question: A space shuttle is in an orbit about the Earth. At its apogee, it uses thrusters and increases its velocity by 400 m/sec. What is the new orbit semimajor axis, eccentricity and how much will the next perigee altitude be increased? Known: Original semimajor axis: 7000 km -> a...

Question: A space shuttle is in an orbit about the Earth. At its apogee, it uses thrusters and increases its velocity by 400 m/sec. What is the new orbit semimajor axis, eccentricity and how much will the next perigee altitude be increased? Known: Original semimajor axis: 7000 km -> a...

So I am asked to rotate by 45 degrees about the y-axis. With the power of the net i found that it is; [ cos(45) 0 sin (45); 0 1 0; -sin(45) 0 cos(45)] i really would like to understand HOW they get this. THANKS in advance!

Homework Statement Two particles having charges q1 = 0.600 nC and q2=5.50 nC are separated by a distance of 1.10 m. At what point along the line connecting the two charges is the total electric field due to the charges equal to zero? Homework Equations Coulomb's Law The Attempt...

I'm trying to understand how to find the axis of a helix but so far I seem to be hitting a blank. How for instance would I go about finding the axis of the helix r(t)=(e^t)costi+(e^t)sin(t)j+(e^t)k ? I would be very gratefull for any and all assistance.

Hi! More than a decade ago, I used to listen to a so-called walking encyclopedia over the radio. One of the radio listeners verified the information that he had read somewhere: That if the Earth revolved on its axis at a much faster rate, then time would become faster. However, this radio...

[SOLVED] Seriously? Moment of Force about a specified Axis So I really thought I understood this. I have attached the problem and attempt at solution. It should be easy to follow. Problem Attempt at Solution This was my process: 1. Write each F and each r as cartesian vectors 2. Find...

Homework Statement A thin, rectangular sheet of metal has a mass M and sides of length a and b. Use the parallel-axis theorem to calculate the moment of inertia of the sheet for an axis that is perpendicular to the plane of the sheet that passes through one corner of the sheet Homework...

i have an orientation of a 3d object in space given by theeta, si and phi i.e. angles which the objects makes with respect to three axis. Now i want to translate the problem such that i get an arbitrary axis rotation about which to some calculated degrees would produce same orientation...

Homework Statement Two thin rectangular sheets (0.23 m 0.35 m) are identical. In the first sheet the axis of rotation lies along the 0.23 m side, and in the second it lies along the 0.35 m side. The same torque is applied to each sheet. The first sheet, starting from rest, reaches its final...

Homework Statement I have to find the kinetic energy of the total system; b has mass 2m and a has mass m. They rotate around the y-axis and and through the origin (0,0). There's two ways of finding the kinetic energy of the system around the y-axis. 1) I find moment of inertia for each...

Hi Guys, I've attached 2 pages from the book of landau "The Classical Theory of fields", I have a question about the lorentz transformations in pages 10,11 after reaching the step: tanh(psy)= V/c How did he split the latter into sinh(psy) and cosh(psy) and added the "gamma" constant...

What I'm about to ask isn't a homework question, but it is a personal question relating to a home-project I'm working on. My question is, what is the moment of inertia of a hollow square tube about an axis perpendicular to its length? Here's a poor diagram: -----|----- (where | is the...

Homework Statement I have a problem that involves a vertical axis that can rotate through a fixed axis located at the very top of the rod, at point A (the axis is coming out towards us, the rod's rotation would look like a pendulum). The rod is nonuniform and there is a block attached to the...

Hi All: If given a set of 3D points data, it's very easy to calculate the covariance matrix and get the principle axises. And the eigenvalue will be the variance on the principle axis. I have a problem that if given a random direction, how do I calculate the variance of the data on the given...

hi there. can anyone please explain to me the parallel axis theorem? the parallel axis theorem states that I = I_cm + M(d^2) where d = distance from the center of mass axis to the parallel axis and M is the total mass of the object. The rotational inertia of a thin rod about the center is =...

Homework Statement A thin rectangular sheet of steel is 0.30m by 0.40m and has mass 0.470kg. Find the moment of inertia about an axis that is perpendicular to the plane of the sheet and that passes through one corner of the sheet. Homework Equations Parallel axis theorem: Ip = Icm +...

[SOLVED] 2 particles moving along x axis. Homework Statement Two particles move along the x axis. The position of particle 1 is given by x= (6.00m/s^2)t^2 + (3.0m/s)t + 2.00m the acceleration of particle 2 is given by: a = - (8.00 m / s^3) t and, at t = 0, its velocity is 20 m / s...

I got this problem and I got the answer 0.5 rad/s^2, but it is not the right one. pls help me. thanks At t=0 wheel rotating about a fixed axis at a constant angular acceleration has an angular velocity of 2 rad/s. Two seconds later it has turned 5 complete revolutions. What is the angular...

The question is: Plot a graph of the acceleration (vertical axis) as a function of the net force for the trials in which the mass remained constant. Draw a line of best fit and calculate its slope. What does the graph indicate about the relationship betweena cceleration and net force? What...

Suppose that a particle's position is given by the expression in the attachment Explain: 1. When does the particle first cross the negative x axis? 2. Find the particle's velocity as a function of time. Express your answer using unit vectors.(e.g., A i_unit+ B j_unit, where A and B...

Homework Statement A sphere consists of a solid wooden ball of uniform density 800 kg/m^3 and radius .20 m and is covered with a thin coating of lead full with area density 20 kg/m^2. A. calculate the moment of inertia of this sphere about an axis through the center. Homework Equations...

Hi Consider a symmetrical beam, where as we know the Neutral Axis (NA) would be at the Geometric Center. If that beam was simply supported at both ends, there would be equal tension and compression to ensure that beam was in equilibrium. Now if we applied a vertical load, downwards, in...

Homework Statement So I have been doing the adding of vectors by using their components and you are suppose to use the + X axis as a reference frame so when 3 vectors are given do you always have to subtract the given theta from the quardrant total ie. 22m, 56 degrees west of south plotting...

Homework Statement I've got a problem that I can't figure out. It deals with strain. I've got a box, sitting on the x-y axis(like normal x-y axis's are). The box extends 4 inches from the origin in the x direction, and 2 inches up. Going clockwise(starting at origin) the corners are...

Homework Statement The region in the second quadrant bounded above by the curve y=-x^3, below by the x-axis, and on the left by the line x=-1, about the line x=-2 Homework Equations It's basically the big radius squared minus the small radius squared, integrated in terms of y, and...

Hi everyone, I'm pretty new to Physics Forums but it seems like a fairly friendly community. :) Homework Statement Determine the equation of the surface formed when the line x=3y is rotated about the x-axis. Homework Equations x=3y is the given line.The Attempt at a Solution First I...

I have recently been reading that the Earth's Axis has tilted 26 degrees further with two of the most significant shifts occurring in December 2006. I read about this and thought... can this be true...how odd that I have been feeling like the sunlight this season seems to be reaching places...

Homework Statement Find the 3 × 3 matrix A such that its transform is the 120 degrees rotation in R3 about the axis through the origin and the point (1, 1, 1). Homework Equations Rotation Matrix in R2: R = (cosx, -sinx sinx, cosx) The Attempt at a Solution My...

Homework Statement I have a cylinder, for which i want to find the inertia tensor. http://www.mip.sdu.dk/~pino/inertiacyl.JPG Where the rotational axis are either the x (red) or y (green). Homework Equations I know that the inertia tensor for a cylinder is of the form...

i only joined this site to post this thing... now today at school (im in gr 10 by the way) a gym teacher came up to me with a football (american) in his hand and said "bassbreaker (not really my name but we'll leave it at that) You're a smart kid, tell me how this happens." and he rotated the...

Homework Statement A uniform square board ABCD had mass 5kg and sides of length 60cm. The board is hinged at A so that it can rotate freely in a vertical plane. A light string of length 1 metre is attached to B and to a point E, 80cm above A. The bards rests in equilibrium with AB horizontal...

Homework Statement A lever of length 3L can rotate freely around a horizontal axis O. The end of each arm "2L" and "L" of the lever has one mass : "4m" and "9m" , respectively. Find the velocity of mass "9m" at the bottom. Consider that the lever was initially at rest in the horizontal...

Homework Statement Find the volume of y = 2x^2 y = 0, x = 2 when it is revolved around the line y = 8.Homework Equations Integral formulas for volumes by discs, washers and cylinders.The Attempt at a Solution Translate the curve so that axis of revolution is along the X axis. Is this the...

Hi, I have this homework question and I completed and found the the foci and the center for the ellipse, but I don't understand how to find the semi major and minor axis. Graph and give the center, semi major and semi minor axis and foci of the ellipse 25x^2 + 350x + 9y^2 - 54y +1081 =...

In a motion about a fixed axis, where the position is r(t) and the angular velocity is w(t), we know that dr/dr = w(t)xr(t). My question, does this equation remains true if the axis vector is changing by the time t? Why so? Thank you.

Homework Statement The question si the make a rotation of axis to elmininate the cross-product term in the work i provided in this pic: http://img295.imageshack.us/img295/9579/untitledtu4.png Homework Equations The Attempt at a Solution I've drawn of the example in the pic I've...

Hi all, I'm trying to compute the axis forces in the construction I put to attachment. I already have computed the R forces, but I don't know where should I start computing the axis forces from, from which point. Could please someone give me some advice? Thank you very much, best regards.

A thin, uniform rod is bent into a square of side length "a". If the total mass is M, find the moment of inertia about an axis through the center and perpendicular to the plane of the square. Use the parallel-axis theorem. According to Parallel Axis theorem: I = I(cm) + Md^2 The...

Homework Statement A uniform stick of mass M = 2.1 kg and length L = 1.3 m is pivoted at one end. It is held horizontally and released. Assume the pivot is frictionless. Find the magnitude in Newtons of the force Fo exerted on the stick by the pivot immediately after it is released. I...

Hello, I have a three axis accelerometer that I am using in project that I am working on and I need to find the angle/vector of the axis’s when the device is not orientated to its designated axis, and when it is accelerating. If I lay the device flat on a horizontal surface and read the...

Homework Statement The rectangle shown has a mass, m. The sides are made of uniform thin wire. The short side is of length a, and the long side is of length b. If m = 5.50 g, a = 0.05 cm and b = 0.1 cm, what is the moment of rotational inertia about the axis indicated? (ignore the x's)...

Homework Statement Explain why applied force is plotted on the vertical axis of the graph even though it is the independent variable in a Hooke's Law experiment (involving a mass being attached to the spring) Homework Equations Fx = kx The Attempt at a Solution Maybe it's because...

Homework Statement The rod of length 2a swings and it rotates \dot{\phi}[/tex]. Find kinetic energy. The Attempt at a Solution I know how to find kinetic energy if we have rotation just in xy plane, but I'm having a problem to understand how to do it with rotation around y axis. If we have...

Hi, I was wondering in a cubic equation such as x³ - 5x = 2x - 1 can be rearranged to x³ - 7x + 1 = 0 is that 0 the y value, and +1 where the line crosses the y axis? Is - 7x the gradient or is x³ - 7x the gradient? Thankyou

find angle and axis of rotation that sends [x1,x2,x3] to [x2,x3,x1] I am not sure where to begin with this.

Homework Statement Rigid rods of negligible mass lying along the y-axis connect three particles (Fig. P10.20). The system rotates about the x-axis with an angular speed of 2.90 rad/s. Figure P10.20 (a) Find the moment of inertia about the x axis. ______kgm2 Find the total...