Position Definition and 1000 Threads

  1. N

    How much does the raft move with change of position?

    heres the problem... and i figured out part a but don't understand how to get the second part, here is what i have done... my question is should the angle be from the point of origin? what I am getting is -2.12 meters in a direction of -45 degrees. is this correct? I'm using x2-x1/y2-y1 to...
  2. D

    Find the equilibrium position of the winch

    Homework Statement A whip made from a material shaped shaft axis radius R and moment of inertia I and a crank with the axis perpendicular to the axis of rotation of length l and mass m, while the rest parallel to the handle - mass ##m_{2}##. It hangs on a hoist that has mass m. Suppose rope...
  3. A

    Horizontal & vertical angle of antenna beams & UE position

    Hi this is my first post here. Sorry for this naive question xD I want to calculate antenna gain for which I need the horizontal Φ and vertical θ angle of an antenna beam. The formula for gain is. is it ok to convert the rectangular coordinates of antenna into spherical coordinates and compute...
  4. Praveen Vijayan

    Uncertainity Principle: possible to know the momentum and position?

    The principle states it is impossible to 'simultaneously' know the position and momentum(velocity)of an object. Position is something that can be noted at a particular instant, as from a photograph whereas velocity is something that can only be measured over a period of time,as from a movie. The...
  5. E

    Position Eigenstates Indeterminacy

    How large could position eigenstates indeterminacy be so as to be indistinguishable from classical state? For example. If a particle is smeared by 10 Planck length.. could we tell or could we consider it as classical state? What is the most accurate device that has probe the smallest region...
  6. S

    Confused by different definitions of position

    Hello, I am self-studying an introductory mechanics textbook and while I feel I understand the material there pretty well, I came across across an online definition of position which seems at odds with the explanations and definitions in my book. The definition that confused me is: ""Position...
  7. S

    Website(s) Listing Postdoc Position for Biophysics?

    Are there websites that specialize in listing postdoc position for biophysics, computational/mathematical biology? I looked through higheredjobs and aps but found very few positions. Are the available positions this few?
  8. gracy

    Position of centre of mass in semicircular disc

    My teacher taught us how to locate position of centre of mass in semicircular disc She said circular disc is made up of two semicircles .It's centre of mass is located in centre .But When one of the semicircles is taken out from the circle , only one semicircle is left out.To locate the...
  9. B

    Time Relative to Position: Yes

    Okay, this is my first post, and I'll have you know that I'm just an amateur. So, I'm not going to get into any complicated mathematics. So basically, is time relative to position? Hypothesis: Yes, it is. Reason: Well, here's a dumbed down version. The Earth's rotation around the sun is what...
  10. P

    Position function and its derivatives

    Okay so I'm currently in cal 3. I've also taken physics 1 and 2. When I first saw the position function differentiated into velocity and then to acceleration I was awestruck. Math is beautiful and divinely structured. That's what I thought. But as I've gone on and worked with it more and more...
  11. Overt

    How Can I Gauge My Postdoc Prospects in Biological Physics?

    I'm nearing the end of choosing a physics graduate school to attend and the decision is coming down to what research groups I'm interested in. My area of interest is in biological physics but I'm not quite sure whether I want to do computational or experimental work. A major factor in choosing...
  12. Cake

    Find Velocity and Position of Mass on Frictionless Table

    Homework Statement This Problem involves solving a simple Diff. Eq. A block of mass m slides on a frictionless table. It is constrained to move inside a ring of radius L that is fixed to the table. At t=0 the block is moving along the inside of the ring (In the tangential direction) with...
  13. C

    Kinematics position function question

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > I'm studying for AP test. This is not a homework question. Does anyone know how to do number 2? I don't even know where to start. I tried factoring out t and using quadratic formula, but I kept...
  14. B

    Explosion-Proof Linear Position Control Sensor: LVDT vs. Ultrasonic Comparison

    Homework Statement , [/B]I have to recommend a linear portion control sensor, that can be used in an explosive enviroment. Unsafe electrical contacts should be avoided and the case must not permit any dust or water.Homework EquationsThe Attempt at a Solution . [/B]My thoughts are either a LVDT...
  15. omega5

    Finding force from position equation

    Homework Statement A 4.50kg crate is suspended from the end of a short vertical rope of negligible mass. An upward force F(t)is applied to the end of the rope, and the height of the crate above its initial position is given by ##y(t) = (2.80m/s)t +(0.61m/s^3)t^3## What is the force at 4...
  16. M

    Language C - Position my Printf in X and Y on the screen.

    Homework Statement I work on Microsoft Visual studio 2010 on Win7. Ok so let me explain the problem here, The functions works very good to position my printf in X and Y on my screen ONLY when my 2D Array labyrinth Map is NOT printed on the screen. But once I printf my Map on the screen I...
  17. A

    How can I make position controlled motor ?

    I have no idea regarding it I just know that we can control a motor movement and can move it both to and fro. please help
  18. Robin04

    Calculate the position of the center of mass

    Homework Statement I would like to calculate the position of the center of mass of the body on the figure. http://kepfeltoltes.hu/150302/161353224K_pkiv_g_s_www.kepfeltoltes.hu_.jpgHomework EquationsThe Attempt at a Solution I read a way of solution: Theorem of Pappus It states that if we...
  19. Y

    Exploring Jet Engine Position: Front or Back?

    Hello. Do you think the idea of placing the jet engine at the front is plausible? Why? Why not? Thanks Yrjosmiel
  20. C

    How to calculate the angles that define the position your arm is in

    I have 3 points ##S##, ##E##, and ##W## each with ##x##, ##y##, and ##z## positions. ##S## is always at ##[1,1,1]## ##S## is connected to ##E##, and ##E## is connected to ##W## by a line. I want to calculate the azimuth and polar angles between ##E## and the vertical, and the azimuth and...
  21. Yam

    What is the Angle Between Velocity and Acceleration Vectors at t=(π/2w)?

    Homework Statement A particle moves in a plane described by the position vector r (t)= ( 2bsin( wt ))i + ( bcos( wt ) )j where b and w are some constants. The angle between its velocity and acceleration vectors at time t=(π/2w) a) is approximately 27 degree . b) is exactly 45 degree . c) is...
  22. S

    Finding the Maximum Positive Transverse Velocity of a Transverse Wave

    Homework Statement A transverse wave is described by y=0.02 sin(30x-400t). Determine the first positive x-coordinate (x>0) for which the transverse velocity of that point in the medium is at its maximum positive value when t=0. All variables are in SI units. a) 5.2 cm b) 10.4cm c) 15.7 cm...
  23. D

    What are the velocity & position of an object as function of time?

    Homework Statement A motorboat is moving across a lake at a speed vo when its moot suddenly freezes up and stops. The boat then slows down under the frictional force fR = -bv (a) What are the velocity and position of the boat as a function of time? (b) If the boat slows down from 4.0 to 1.0 m/s...
  24. ellipsis

    Calculating apoapsis from position and velocity

    I have a body of negligible mass orbiting a body of considerable mass, with that larger body fixed at the origin. I am given the orbital state vector (position and velocity), and need to return the apoapsis of orbit. Other orbital information would be useful, e.g. energy, angular momentum...
  25. W

    Velocity and Position with Friction

    Homework Statement A 27kg box is being pushed across the floor by a constant force https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png96,0,0https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngN. The coefficient of kinetic friction for the table and box is 0.14...
  26. DaveC426913

    USB Eyepiece for Microscopes: Quality Viewing from Any Position

    I stumbled across this. http://www.innovatoys.com/tech-gadgets/usb-eyepiece-for-microscopes/5937 I've got a 6" reflector on an equatorial mount. At some angles, an hour of viewing could put me in a chiropractor's office. It would be cool to observe the sky from a sitting position that didn't...
  27. Wayland Bugg

    Rope tangent angle over pully given position of offset load

    I am trying to symbolically resolve the angle of rope that suspends a load (rectangle) between two pulleys given the length of rope that is let out over the pulleys. See attached image. the load is not intended to move horizontally, only vertically. so you can imagine each pulley must have an...
  28. Fantini

    MHB Calculation of the commutator of the hamiltonian and position

    The book calculates the commutator $[H,x_i]$ as $$[H,x_i] = \left[ \sum_j \frac{p_j^2}{2m}, x_i \right] = \frac{2}{2m} \sum_j p_j \frac{\hbar}{i} \delta_{ij} = - \frac{i \hbar p_i}{m},$$ where the hamiltonian operator $H$ is $$H = \sum_j \frac{{\mathbf p}_j^2}{2m_j} + V({\mathbf x}).$$ The book...
  29. P

    Calculating change in linear position

    I would like to calculate the change in linear position of a point on a bar whose center of mass is changing as the bar rotates. Assume an angular velocity of pi-rad/s, a negligible mass for the bar, and a mass of 1-kg for the weight (which is what is moving and causing the center of mass to...
  30. little neutrino

    Gravitation - Position of Stable Equilibrium

    Homework Statement A particle of mass 3m is located 1.00 m from a particle of mass m. You put a third mass M so that the net gravitational force on M due to the two masses is exactly zero. Is the equilibrium of M at this point stable or unstable for points along the line passing through M and...
  31. Ryuzaki

    Question concerning the expected position of an object

    Suppose there's an object within a sphere of radius 5-metres from a given point P=(x_0,y_0,z_0). The probabilities of the object being within 0-1, 1-2, 2-3, 3-4 and 4-5 metres of P are given to be respectively p_1,p_2,p_3,p_4 and p_5. With this information, is it possible to find the expected...
  32. P

    Finding Position from Equations of Motion at Different Times

    Usually, equations of motion (with constant acceleration) are written in terms of values of position/velocity at time ##t=0##. Take for example: $$x = x_0 + v_0t + \frac{1}{2} a t^2$$ Where ##x_0## and ##v_0## are the values (at ##t=0##) of position and velocity respectively. What if we're...
  33. D

    Understanding Position Derivatives: Does Logic Follow?

    This might be a very vague and unclear question, but let me explain. When an object at rest moves, or moves from point A to point B , we know the object must have had some velocity (1st derivative of position) during that trip. It's also true that the object had to have accelerated to gain that...
  34. P

    Are observables like position emergent properties?

    Title basically says it all. I'm a physics undergrad trying to wrap my head around quantum physics, and I was hoping people here could help. My question comes from something in one of my textbooks. It tries to explain particle-wave duality through a piece of string, which I'll quickly go over as...
  35. D

    We can perceive position, velocity, acceleration, jerk

    We can perceive position by establishing a reference point We can perceive velocity by noticing a change in position We can perceive acceleration by noticing a change in velocity We can perceive jerk by noticing a change in acceleration Can humans also perceive jounce or any higher order...
  36. K

    Relative position and velocity question (Two dimensions)

    Homework Statement A freight train is moving at a constant speed of 10 m/s. A man standing on a flatcar throws a ball into the air and catches it as it falls. Relative to the flatcar, the initial vellocity of the ball is 15 m/s straight up. a. What are the magnitude and direction of the...
  37. D

    Position and speed are enough in a physical system?

    I've recently read in this article http://www.en.uni-muenchen.de/news/newsarchiv/2013/f-m-77-13.html that "In the world of classical mechanics, the state of a physical system and its future evolution is fully determined by the instantaneous locations and velocities of its constituent particles"...
  38. B

    Why Is My MATLAB Program Returning Incorrect Values for Airplane Path?

    Hello I've just subscribe because I've a problem with a project. First, I'm a student in France, in prep school. My team and I are working on a project : we study the perfect path for an airplane to be in micro-gravity (it means the only acceleration is the one due to gravity, like what we have...
  39. S

    Integral to determine position probability.

    There is something that I just want to make sure I am understanding. I read once before that ∫ababs(ψ)2 dx will give you the probability that your particle will appear in region between x=a and x=b. Note: abs(ψ)2 means the square of the magnitude of the wave function. I just couldn't find any...
  40. S

    Where Should the Slider Be Positioned on a Loaded Potentiometer?

    Homework Statement The problem that is that of a loaded potentiometer and the position on the slider. The question is that a 10k Ohm potentiometer is connected across a 9 volt dc supply. Across the bottom part of the POT a 5k Ohm resistive load is connected which has 3 volts developed across...
  41. S

    Unraveling the Concept of Energy Position in Classical Physics

    In classical physics, does energy have a position? It seems rather obvious that kinetic energy can be regarded as a property of a moving mass.. If carry a cup of hot coffee from one room to another, it seems clear that I have transported heat energy. That indicates that energy can also...
  42. Selayna

    Solving for final position with a negative work value

    Homework Statement An object is acted on by the force shown in the picture shown below: What is the final position of the object if its initial position is x = 0.50 m and the work done on it is equal to -0.29 J? Initial position = Xi = 0.5 m Work = W = -0.29 J Force = F displacement = d...
  43. Fantini

    MHB Momentum operator in the position representation

    Hi! :) I'm trying to understand the following calculation. The book Quantum Mechanics by Nouredine Zettili wants to determine the form of the momentum operator $\widehat{\vec{P}}$ in the position representation. To do so he calculates as follows: $$\begin{aligned} \langle \vec{r} |...
  44. A

    Exploring Wavenumber & Position Eigenstates

    If the wavenumber eigenstates are |k> and the position eigenstates are |x>, then my notes say we can write |k>=∫-∞∞ek(x)|x>dx i.e express a wavenumber eigenstate in terms of a superposition of position eigenstates. Now they state that ek(x)=eikx/√(2π). I don't understand how we can say that the...
  45. littlejon

    A position versus time graph involving the unit circle

    Homework Statement Homework Equations v(x)t= -wAsin(w+o) The Attempt at a Solution -5(10)sin(0)= 0 D is this the right procedure?
  46. 9

    Kalman filter - help me to set up a state equation

    I would like to find the distance that a vehicle travels using a Kalman filter. The vehicle is a car that travels the road between two positions. The vehicle has a GPS/barometer/accelerometer device that collects position data, which I converted from a longitude and latitude to a North, East...
  47. 2

    Variance in position for the infinite square potential well?

    [Note from mentor: this thread originated in a non-homework forum, therefore it doesn't use the standard homework template] ------------------------------------------ This exercise pops up in the Cavendish Quantum Mechanics Primer (M. Warner and A. Cheung) but I can't seem to figure it out. So...
  48. 9

    Two measurements from different sources - how to combine?

    I can get a measurement of my distance between points (x1,y1,z1 and x2,y2,z2) by analysing position data from a GPS/barometer system, which has a standard deviation of about 2m for x y z positions. I can also analyse data from a system that provides velocity with a standard deviation of about...
  49. F

    Position & Momentum: Understanding Expectation Values

    Good morning- afternoon. First of all, apologize for my bad English. After reading about how the expected value of an operator <q> is what we would measure in classical mechanics and that for the case in which we have various of them it is not trivial to deduce in which order these operators...
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