Frame Definition and 1000 Threads

A vehicle frame, also historically known as its chassis, is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism.
Until the 1930s, virtually every car had a structural frame separate from its body. This construction design is known as body-on-frame. By the 1960s, unibody construction in passenger cars had become common, and the trend to unibody for passenger cars continued over the ensuing decades.Nearly all trucks, buses, and most pickups continue to use a separate frame as their chassis.

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  1. K

    Working out support reaction of a frame - Statics

    Homework Statement For the frame shown (see attached picture) , work out the horizontal reaction at B (ie find Bx)Homework Equations EQUILIBRIUM EQUATIONS: sum of moment = 0 (CCW is positive) sum of vertical forces = 0 (up is positive) sum of horizontal forces...
  2. 7

    How can I calculate forces on a vehicle frame?

    I am working on an SAE Baja vehicle for a competition as part of my coursework requirements. Right now I am trying to come up with a method to estimate the forces that the frame will be subjected to. I need help doing this. I know that the top speed will be 30mph and that the vehicle will weigh...
  3. A

    Problem involving a rotating frame. Help

    This is a conceptual problem which I am facing for many days. If we convert a scenario in an inertial frame into a rotating frame, we apply a pseudo force i.e. centrifugal force radially outwards on the particle. Right? Also if a particle is having a circular motion in any frame of...
  4. A

    If moving object decelerated into your frame, will it lengthen?

    Let's say something is moving very fast past you. You see the thing to be length contracted. But let's say that thing suddenly slows down very fast and enters your inertial reference frame. Will it suddenly appear to you to have lengthened? My tutor said that this is not the case because of...
  5. S

    Question about noninertial reference frame.

    Homework Statement If you are in a noninertial reference frame, that means: Homework Equations The Attempt at a Solution I know that nonintertial reference frame is something that is moving. However, if I am in it, then should I be moving together with it?
  6. M

    Acceleration overcoming Velocity. Over what time frame?

    Homework Statement A particle leaves its initial position Xo at time t=0, moving in the positive x direction with speed Vo but undergoing acceleration a in the negative x-direction. Find expression for (a) the time when it returns to Xo and (b) its speed when it passes that point I'm...
  7. J

    Velocity change by force in one and two inertial frame confusion

    Hi, I just finished class and my professor was writing some of Newton's Laws on the board and derived some equations. We ended up with: V(Δt)=FΔt (this is for velocity in first inertial frame V(2Δt)=2FΔt (this is for velocity in second inertial frame Then he went and got the position in...
  8. B

    Design of Concrete Structures: Solving a Tricky Frame Question from Past Exam

    Hi the following question is from a previous exam for the subject Design of concrete structures, just wondering if I can get any pointers as I was not able to find the reactions.
  9. X

    What is the motion of K' in the direction of the x-axis?

    Homework Statement Find a system K' in which the following events in frame K appear at the same time: i) x1 = a; t1 = (2a) / c; y1 = 0; z1 = 0 ii) x2 = 2a; t2 = (3a) / (2c); y2 = 0; z2 = 0 Describe the motion of K'. Homework Equations Lorentz transformations; time dilation...
  10. M

    How is the Inner Product Expansion in Holomorphic Bundles Derived?

    let x a point on complex manifold X, z_j a coordinate system at x , E a holomorphic bundle and let h_α be a holomorphic frame of E. After replacing h_α by suitable linear combinations with constant coefficients we may assume that h_ α is an orthonormal basis of E_{x}. Then an inner product <h_α...
  11. G

    Frame for lighter-than-air aircraft.

    Hello everyone. I have been trying to think of some practical and cheap airship designs. I have done some calculating, and if you were to have an airship's envelope in a cylindrical shape that is 300' long and 75' in diameter, it would be able to lift approximately around 45 tons if filled with...
  12. A

    Relativistic Doppler and preferred frame

    To my understanding the Relativistic Doppler shift is a product of the classical velocity shift and the dilation factor arising from that velocity. The classical effect can be red or blue depending on whether the emitter and receiver are receding or closing respectively. The dilation...
  13. A

    Why is the cm frame beneficial for collisions?

    I have never understood why it's beneficial to do a collision in the cm frame, but then I did an example for myself and it was easier. I just don't understand why. I had two objects with masses m1 and m2 and velocities v1 and v2. I found the velocity of the centre of mass: vcm =...
  14. V

    Age of the universe in earth's reference frame?

    I understand that the ~14.6 billion year age of the universe is in the cosmological frame, i.e., representing the coordinate time elapsed in a comoving reference frame. Of course this means (as has been discussed plenty of times here) observers in different frames would measure a different age...
  15. T

    Force vector in a new coordinate frame?

    Homework Statement http://img811.imageshack.us/img811/9092/captureykj.png The Attempt at a Solution The answer is also in the image above. I have no clue how to start this question. Could anyone be so kind to give me a hint on how I should approach this question? Thanks!
  16. E

    Find a vector to a particle from a rotated reference frame

    Homework Statement Consider a particle in space whose position vector from the origin of reference frame i is given by the expression r(Oi to P) = 37t(Ii + Ji + Ki). The distance vector from the origin of another reference frame (m) to the origin of the I reference frame is given by r(Om...
  17. W

    How exactly to obtain Frenet Frame via Gram-Schmidt process?

    I have a regular curve, \underline{a}(s), in ℝN (parameterised by its arc length, s). To a running point on the curve, I want to attach the (Frenet) frame of orthonormal vectors \underline{u}_1(s),\underline{u}_2(s),\dots, \underline{u}_N(s). However, looking in different books, I find...
  18. Z

    Frame Deflection: Solve for B Deflection + Reactions @ A & D in 3-4 Lines

    I had this as an exam question in my first Structural Analysis course, and couldn't figure it out. The frame is supported by 2 cantilevers at points A and D. The top member is perfectly rigid, that is EI=infinity. E is constant. Solve for the deflection at point B and the reactions at A and D...
  19. V

    Is reference frame important when looking at work done?

    It must be, right? Obviously, if you're pushing a block by exerting a force F on it over a distance D on the ground, if you are in the frame of you or the block, your distance is 0 so it appears you're doing no work. I ask this question because I was doing a practice problem that should be...
  20. Chestermiller

    Definition of Frame of Reference

    In studying SR, I've been subscribing to a particular definition of a Frame of Reference that makes sense to me. Recently, I've been made aware by another PF member that there may be other, broader, definitions that are valid and that people use. I would like to know more about these broader...
  21. S

    Observer Frame of Reference

    Practicing Lorentz transformations but still not absolutely clear about conditions for observer's frame of reference. For example: Suppose that just as one of Einstein's long and surreally fast trains is passing a station platform, lightning strikes the platform at two points making scorch...
  22. N

    The divergence operator in a rotated reference frame

    One can easily prove that \nabla \cdot f is invariant under a rotation of the reference frame, however I would like to prove that the divergence operator itself is invariant (same principle, different approach). In other words I want to prove that \mathbf \nabla = \mathbf e_x...
  23. R

    2-node Frame FEM element thermal formulation

    \inthi all, I need just little bit of confirmation about what I'm doing. Normally I know how the stiffness matrix is composed for 2 node frame element in 3D space. which creates 12x12 matrix for that element, if there is also thermal loading on frame element additional...
  24. C

    Transform a pde into rotating frame

    Hi, I have an equation of the form; \frac{d}{dt}(W) = \omega \left(x \frac{\partial}{\partial y} - y \frac{\partial}{\partial x} \right) W + g \frac{\partial}{\partial y} W + k x \frac{\partial^2}{\partial y^2} W I want to change it into the rotating frame using the transform; x...
  25. P

    Space-Saving 2-Piece Hammock Stand: A DIY Solution for Lateral Pull on Walls

    I want to put a hammock in my room but don't want to damage the walls from putting too much lateral pull on a 2X4 stud. So I decided that I need a hammock stand, but don't want a huge ugly thing spanning my room. Do you think its possible to build two separate free standing supports that can...
  26. S

    Problem on frame of reference in rotation

    Homework Statement I wanted to know if I consider the frame of reference as a rotating body itself, then will the points lying on the body rotating be stationary with respect to the rotating frame of reference? Homework Equations None The Attempt at a Solution As per me, if I am...
  27. Telemachus

    Generalized momentum and Hamiltonian over a non inertial reference frame

    Hi there. I need help to work this out. A particle with mass m is studied over a rotating reference frame, which rotates along the OZ axis with angular velocity \dot\phi=\omega, directed along OZ. It is possible to prove that the potential (due to inertial forces) can be written as: V=\omega...
  28. TrickyDicky

    Does gravity as a fictitious force do work? (GR's free-falling frame POV)?

    This discussion started as a side clarification of something in this thread https://www.physicsforums.com/showthread.php?p=3971013#post3971013 and although tangentially related it probably deserves a thread of its own so anyone can participate without reservations. Please keep in mind I am not...
  29. M

    Retrofitting a Disc Brake on an Aluminum Track Frame

    Hello everyone, I am a new member here. Nice place you have; I have been reading on here again and again and figured it would be the right place to ask you about a problem I just can't get sorted out myself. It is about bicycles and disc brakes. I have an aluminum track frame that I want a...
  30. V

    No redshift in a freely falling frame

    Why is there no redshift in a freely falling frame? The photon in a freely falling frame also rises in the gravitational field, so isn't it supposed to be redshifted?
  31. K

    An elevator Physics Accelerating Frame

    An elevator slows down with a 6 m/s2 acceleration and an object m=3 kg is freely released as shown in figure There is no friction between object an semispherical shape. The object reaches L point what is the force which the object exerts L point? A)120 N B)240 N C)360 N D)480 N E)600 N...
  32. aleemudasir

    Object moving at speed of light as Reference frame.

    Is there any other object except photon which moves at the speed of light? Why can't an object moving at the speed of light be taken as reference frame? Can we use the equation m=m(0)/sqrt(1-v^2/c^2) for an object moving with speed of light?
  33. Q

    Question on waves propagation from a moving frame

    In my book on waves, it is said that, given a flexible string under tension, a derivation of the transverse velocity v can be given by viewing the string in a frame moving uniformly with a velocity equal to that of the wave itself. The velocity can be found by requiring the uniform tension of...
  34. H

    How does frame dragging cause a stick to rotate in the opposite direction?

    Now, I've read that frame dragging will cause an effect likened to planetary gears, where the spinning source is the sun gear and the object is the planetary gear. Here's where I get confused. Suppose you had a straight meter stick aimed directly at a massive rotating object from an...
  35. P

    Frame of reference for Fermi Golden Rule

    Hi guys. I am currently studying Sub-atomic physics and it seems to me that there are different formulas that work in different frame of reference. In particular, I would like to ask: 1. Which frame should we use in applying Fermi's Golden Rule? (I've read somewhere that the matrix element...
  36. A

    Velocity of Frame 2 WRT Frame 1: Time, Distance & Big Bang

    I meant which frames distance divided by which frames time gives the velocity of frame 2 wrt frame 1..I guess the 'v' measured from rest frame is different from v measured from other frame right(concerning time dilution since time always dilutes in frame 2 only).? Btw do u think their is a...
  37. D

    Determining time frame for most recent geological layers

    What significant features are present in the five or six most recent geological layers? In other words what is the basis for determining how much time has elapsed in these layers? Is it mostly based on the types of fossils or the types of soil or rocks in these layers? Also, is it easier or...
  38. P

    Newton's law in non inertial frame.

    Please explain the concept of pseudo forces by considering an example of two cars say A and B, accelerating in the same direction. How will Newton's law applied to the man in car B as noted by the man in car A differs from that of the man standing on the earth? And how will the man in car A...
  39. J

    Calculate relativistic com frame for two particles?

    Does anyone know of a standard way of calculating the com frame velocity for two particles moving at arbitary velocities in the lab frame? It's strange that this standard result isn't even in Goldstein's et al book
  40. S

    Basic question about inertial reference frame

    I have no background in relativity. Recently I started reading some introduction to special relativity in Griffith's EM book, where he vaguely defined an inertial reference frame as one in which Newton's first law holds. Now according to this definition, does such frame exist in nature? On...
  41. N

    Transformation matrix from global to loca frame

    Hello friends Iam naveen and new to this forum.I have a question regarding the transformation matrix from world frame to the base frame of a Spatial serial manipulator. The frames are attached like this. The Z-axes are along the link lengths. The Xi axis is oriented such that Xi = Zi X Zi+1...
  42. S

    Solving a FRAMEwork Static Problem - Find Correct Solution

    [b]1. every member is 0.45m and all the angle is 45degree... C is fixed support, D is roller support [b]3. Ʃfx = 0 , Cx = 0 Ʃfy = 0 , Cy + Dy = 20N ƩMc = 0 , 20(0.45) + Dy(0.45) = 0 Dy = -20N...
  43. S

    Why Is the X-Component of the Electric Field Unchanged in a Moving Frame?

    I'm trying to understand why the x-component of electric field is the same in the rest frame and the frame moving in the x direction. I thought I should just be able to write the force four vector in the rest frame and transform it. Symbols with arrows are four vectors...
  44. E

    Frame Dragging Explained: Dimensions, Schwarzschild Radius, Metrics & Angles

    Can someone please explain to me (it can only be brief, I'll try to do the dirty work myself ^.^): Frame dragging in terms of: What is a frame, What are it's dimensions (2d/3d(x,y,z)) What does this have in relation to the Schwarzschild radius in terms of astrophysics; With that...
  45. bayan

    Frame of reference and relativity.

    Homework Statement You are flying your personal rocketcraft at 0.9c from Star A toward Star B. The distance between the stars, in the stars' reference frame, is 1.0 ly. Both stars happen to explode simultaneously in your reference frame at the instant you are exactly halfway between them...
  46. L

    Non inertial or inertial reference frame?

    Homework Statement Specify and explain whether the following is an inertial or non-inertial observer: An observer is placed on a rock between Andromeda and the Milky Way. Homework Equations N/a The Attempt at a Solution So here is my understanding, the observer would be situated...
  47. B

    Does the energy of light depend on the observer's reference frame?

    Hi, Physics Forums! This is my first post here and I know just about zero physics, so I apologize in advance if the question is a little daft/naïve. Ok, so here's what I'm wondering: suppose you have a light source that produces EM waves in all directions at some frequency ν, and a camera set...
  48. A

    Relativistic collision in CM frame at small angle

    Homework Statement Find CM energy of a mu+ mu- collider, with each beam having an energy E of 500 GeV. The beams cross at a small angle of 250 mrad.Homework Equations E^2 - p^2c^2 = m^2c^4The Attempt at a Solution So I have a diagram for the lab frame which has the mu- coming in at a small...
  49. G

    Reaction force, Bending Moments on a sub frame

    Hi, I've been working on a tubular sub frame, that I want to attach to a main frame. The attached shows the sub frame in black lines. The main fram is in purple. There are only four connection points and a force pushing down on each side. When I check for the reaction forces and make...
  50. J

    Can we extend our inertial frame globally?

    People tell me that we cannot extend our inertial frame, as defined in special relativity, across the Universe because that would be in violation of general relativity. The problem is that general relativity says that space-time can be curved whereas a global inertial frame assumes flat...
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