Dynamics Definition and 1000 Threads

General Dynamics Corporation (GD) is an American publicly traded, aerospace and defense corporation headquartered in Reston, Virginia. As of 2020, it was the third-largest defense contractor in the United States, and the third-largest in the world, by sales. The company is a Fortune 100 company, and was ranked No. 83 in 2020.Formed in 1954 with the merger of submarine manufacturer Electric Boat and aircraft manufacturer Canadair, the corporation today consists of ten subsidiary companies with operations in 45 countries. The company’s products include Gulfstream business jets, Virginia- and Columbia-class nuclear-powered submarines, Arleigh Burke-class guided-missile destroyers, M1 Abrams tanks and Stryker armored fighting vehicles.
In 2020, General Dynamics had worldwide sales of $37.9 billion and a workforce of more than 100,000 full-time employees. The current chairman and chief executive officer (CEO) is Phebe Novakovic.

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  1. L

    A sphere rolling without slipping down a hemisphere

    a) From impulse-momentum theorem I have: ##J=mv## so ##v=\frac{J}{m}## and since the ball doesn't slip ##v=\Omega b## so ##\Omega=\frac{J}{mb}## and ##\dot{\theta}=\frac{v}{a+b}=\frac{\Omega b}{a+b}##. b) I considered the angular impulse: ##-J(a+b)=I_0 \Omega_0 \Rightarrow...
  2. K

    I Exact dynamics of spin in varying magnetic field

    Consider an uncharged particle with spin one-half moving with speed ##v## in a region with magnetic field ##\textbf{B}=B\textbf{e}_z##. In a certain length ##L## of the particle's path, there is an additional, weak magnetic field ##\textbf{B}_\perp=B_\perp \textbf{e}_x##. Assuming the electron...
  3. Eko

    Understanding Gas Dynamics in Piston-Crank Slider System

    I need help understanding what happens to the gas that is being worked by the piston, in the crank slider. My goal is to produce linear motion on an object up to a certain height and I'm wondering since the slider moves back during the rotation of the crank what happens to the object I'm trying...
  4. Astronuc

    I Jupiter atmosphere, turbulence and ocean fluid dynamics

    Ocean physics explain cyclones on Jupiter https://phys.org/news/2022-01-ocean-physics-cyclones-jupiter.html Moist convection drives an upscale energy transfer at Jovian high latitudes https://www.nature.com/articles/s41567-021-01458-y...
  5. WhiteWolf98

    [Structural Dynamics] How to model a 3D wing as a 2D Wind Tunnel Model

    Greetings Good People, As the title suggests, I'm having some trouble getting to a 2D model. The process is to select an aircraft (or wing model), and model it as a 2D, 2DOF wing-tunnel model. The aircraft I selected was a Cessna 172. This had a tapered wing, which after some calculations and...
  6. a sad student

    Tetherball rope wrapping around a pole

    My work so far is pretty basic, but I'm not too sure how to continue off from here. I haven't included the 2 dimensional aspect of it either, but I would presume that the rate of decrease in length is more sped up in that case? Would appreciate any help :(
  7. vanhees71

    I Manuscript on elementary rigid-body dynamics

    In view of questions occurring from time to time in this forum, I've written an elementary introduction to rigid-body dynamics (mostly about the force-free and the heavy symmetric top). I hope, it's of some use: https://itp.uni-frankfurt.de/~hees/pf-faq/spinning-top.pdf
  8. W

    MHB Neuronal Dynamics Passive membrane equation

    Hi guys, I am able to solve dif equation of passive membrane model. But later, author says following instructions to integrate first model. Even though I can solve the dif equation of model, I couldn't achieve the solution. Could you help me pls. Best regards.
  9. erensatik

    The Physics of Wheel Movement: Exploring the Dynamics of Torque and Energy

    Why the wheel moves? I intuitively think that it should move to right but I don't really understand why. When AB gets longer by x each end gets longer by x/2 so W goes to right and down. This will create torque and body will move. This explanation seems valid but I can't calculate anything and...
  10. greg_rack

    Conservation of linear momentum, undergrad particle dynamics

    Hi all, I'm opening this thread because of my uncertainty in how to correctly approach this exercise. My first thought was that, since the plate is subject to friction with the floor, it is going to stop, thus the final moment is 0. Hence, from the conservation of linear moment: $$m_Av_A+\sum...
  11. R

    Real-life phenomenon/application of this fluid dynamics model

    Hi! Water is flowing in a converging duct, with the angle α, see the figure. My task is to find a real-life phenomenon / application of this model, and later solve it numerically / analytically where this fluidproblem occurs. However, my imagination is kinda slow today, what are some fun /...
  12. curiousPep

    I Solving Euler's Dynamics Equations for a Gyro-Compass

    Hello, I know it might sound silly but sometimes I get confused. Let's say I have a gyro-compass and I get 3 equations of torque for the 3 axes. I am expected to find the equation of motion and two of them are equated with 0. These are the Euler's dynamics equation with moving reference frame...
  13. Leo Liu

    Notation in fluid dynamics: A circle with a horizontal bar inside

    I came across this notation when reading the wiki article on Venturi effect, which baffled me. Can someone please tell me its meaning?
  14. Mr_Allod

    Analysing the Normal Modes and Dynamics of a Cluster of Atoms

    I am trying to analyse the dynamics of a cluster of 79 atoms. The system can be described with: ##\omega^2 \vec x = \tilde D\vec x## Where ##\omega^2## (the eigenvalues) are the squares of the vibration frequencies for each mode of motion, ##\tilde D## is the "dynamical matrix" which is a...
  15. Einstenio

    Motion of a Particle: Solutions & Examples

    This is jut an example to illustrate my doubt. I don't know how to obtain the tracjectory given only the acceleration in this format. I realized that if i can show that there is an constat vector 'a' that satisfy a•r=constant, than the motion would be on the surface of a cone. So i tried to make...
  16. T

    Elastic collision: Determine the deceleration

    My approach so far is to use F = ma. The forces acting on the block in the horizonital direction are friction and the force of the spring. Choosing the direction towards the spring as the positive axis. Therefore: F = ma -Fr - kx = ma Solving for a = (-Fr - kx)/m If I plug in values I end up...
  17. T

    Dynamics of Four Bar Link using Hamilton's Principle with Loop Closure

    Summary:: Can someone point me to an example solution? Hello The attached figure is a four bar link. Each of the four bars has geometry, mass, moment of inertia, etc. A torque motor drives the first link. I am looking for an example (a simple solution so I can ground my self before...
  18. L

    Amplitude of oscillation of a mass which is the pivot of a pendulum

    1) By conservation of mechanical energy we have ##m_2gl(1-\cos(\alpha))+m_1gl=\frac{1}{2}m_1v_1^2+\frac{1}{2}m_2v_2^2+m_1gl## and by conservation of linear momentum along the x-axis we have ##m_1v_1+m_2v_2=0## which gives us ##v_2=\sqrt{\frac{2m_1gl(1-\cos(\theta))}{m_1+m_2}}## and...
  19. L

    What is the final angular displacement of a disk hit by two masses?

    1) By conservation of linear momentum: ##m_1 v_1-m_2v_2=(m+m_1+m_2)v_{cm}\Rightarrow v_{cm}=\frac{m_1}{m+m_1+m_2}v_1-\frac{m_2}{m+m_1+m_2}v_2=\frac{3}{8}\frac{m}{s}##; 2) By conservation of angular momentum: ##-Rm_1v_1-Rm_2v_2=I_{total}\omega=(I_{disk}+m_1R^2+m_2R^2)\omega## so...
  20. F

    Looking for a book on many body Newtonian dynamics (point masses)

    Any book on many body Newtonian dynamics?
  21. L

    Mass m sliding without friction inside a rotating tube

    1) To be in equilibrium, it must be $$\begin{cases}F_{centr}-T=0\\ T-mg=0\end{cases}\Rightarrow F_{centr}=T=mg\Rightarrow m\omega^2 R_0=mg\Rightarrow R_0=\frac{g}{\omega^2}$$ 2) It is intuitive that this equilibrium is unstable but I don't know how to formally prove this. 3) In ##R_0## the...
  22. A

    B Projectile motion — Thinking about forces on a curve ball

    When a ball is thrown such that it moves in a curved trajectory in the horizontal plane, it amuses me to think of its dynamics. In motion of a ball thrown upwards the force of gravity gives it a parabolic trajectory However when the ball is thrown to curve and hit a target, (in the horizontal...
  23. R

    Courses What do I do to catch up on Physics 1?

    I am a nanobiology student about to start her 2nd year. This year I only had 2 physics courses and I did pretty bad in both. As I start my second year I would like to be very prepared in physics since we will have way more of this subject. Are there some books or tips you have to catch up on...
  24. Johan M

    Simplified rocket lateral dynamics model sign convention

    Hi everyone :smile: . I had came across a simplified simplified rocket lateral dynamics model :https://github.com/build-week/hover-jet/blob/feature/start-design-scripts/design-scripts/jet_vane_speed.ipynb . It has vanes at the exit which generate lift force and can control the rocket...
  25. D

    Gr. 12 Dynamics -- A performer being lifted up by two ropes

    1. break down 430N [Up 35* L] into components 430 cos 35 = 352.2N [L] 430 sin 35 = 246.6N 2. ΣFx= 352.2N [L] ΣFy= 246.6N + 280N - 430N ΣFy = 86.6 3. Pythagorean theorem with the two will give you a magnitude of 362.7N Then using tan you can find the angle of [L 76 U] This method was...
  26. M

    Engineering Rotation around fixed axis (robot arm), dynamics

    Hello, Given the figure below, and the following statement: "The robot arm is driven by two hydraulic cilinders A and B which brings point D rotates CW. The gear in point D has a angular velocity of 5 rad/s. Calculate the velocity and acceleration of the part in point C." First I determined...
  27. Angelo Pascal

    What Are the Key Characteristics of Inertial Waves in Uniform Rotation?

    (a) Write down an expression for the velocity field corresponding to uniform rotation. Find the vorticity corresponding to this flow. (b) Consider a small perturbation u' to the state of uniform rotation with angular velocity Ω, which has the form of a plane harmonic wave u'= A exp i(k·x−ω t) +...
  28. R

    What is the potential energy of a system with N cubes at equidistant heights?

    I have tried to apply the conservation methods, but I am not understanding what the statement is asking for.
  29. A

    Dynamics of a double atwood machine

    I think the equations should be 𝑇−𝑚2𝑔=𝑚2𝑎1 𝑚3𝑔−𝑇=𝑚3𝑎1 𝑇1−𝑚1𝑔=𝑚1𝑎2 2𝑇−𝑇1=(𝑚2+𝑚3)𝑎2 P.S.- My textbook assumes T1 = 2T. I don't understand why that is so.
  30. JamesBennettBeta

    Machine Dynamics: Manual Air Pump Calculation (please check my answer)

    mentor note: moved from ME forum hence no HW template. Summary:: I am stuck into this problem for almost a week now. I think I solved it, but it seems something is wrong. Can someone point me, what is wrong here. It'll be so much helpful. I am stuck into this problem for almost a week now. I...
  31. B

    B Are Decimal Points As Significant In Population Dynamics....

    As they are in engineering and manufacturing? I ask because during a very deep, post stroke marbles census in came to light that I had an extraordinarily high level of pattern recognition such that the department head said I was in the top .003 percent of the population. I ran the numbers...
  32. Prez Cannady

    A Question about extragalactic stellar motion

    We have direct mass models of stellar motion inside of galaxies (basically, find a happy medium between a sphere and a disc). And of course dark matter corrections to explain the deviation between model and observation. Is there any pattern at all to the motion of extragalactic stars passing...
  33. Uchida

    Dynamics motion problem with a disk in contact with a bar

    First, I tried to model the disk-bar as a crank connecting rod, to the OA bar, and apply this: VP = VB + ω_BP x r_P/B, where P is the contact point between the disc and OA bar. I assumed VP = VP sin 30º i + VP cos 30º j (direction parallel to r_P/B), where r_P/B = sin 30º i + cos 30 j This...
  34. H

    I Oort Cloud Dynamics: Interaction, Composition, Hazards

    1. Assuming the Oort Cloud of the Solar System stretches 'almost' to our nearest Star neighbour, how would it interact with that Star's 'Oort Cloud'? I imagine objects constantly colliding between the two systems perhaps causing them to leave the cloud. 2. Does the Oort cloud form a ring of...
  35. R

    Dynamics question -- 3 masses on a pulley-rope system on an inclined plane

    This image was provided, I've completed the first part of the question and got a = 4.8m/s^2 as well as T1= 24.5N and T2=34.3N. not sure about my answers though. also I don't understand the mass in static equilibrium part, can anyone explain how to solve that? Thanks.
  36. Pipsqueakalchemist

    Engineering Dynamics question — Belt pulled between two cylindrical rollers

    For question, in the solution when setting up the moment equation, why does the solution use Fa and Fb? Friction is coefficient times normal force and that can be found with the info given so why does the solution take it to be an variable?
  37. Pipsqueakalchemist

    Engineering Dynamics rigid body cabinet problem

    So for this question I understand part A but part B is confusing me, when using point B as the centre of the moment, I get different sign for the mad term. If you take clockwise as positive than 100N force and the force at point G are causing a positive moment and gravity is causing an negative...
  38. Pipsqueakalchemist

    Engineering Dynamics homework — Does this cabinet sliding on the floor tip over?

    So for this question, when using point B as the centre of the moment, I get different sign for the mad term. If you take clockwise as positive than 100N force and the force at point G are causing a positive moment and gravity is causing an negative moment. But the solutions have different signs...
  39. Lord Doppler

    Engineering Solving Car Suspension Modeling: Understanding Input Forces and Movement Types

    Hello, I'm trying to solve this problem but I'm confused with some things, is correct that in the system there are two input forces, the torque and u(t)? I assumed that the system has two free levels, which are the z displacement and theta (rotational movement), so the system has a linear...
  40. Frabjous

    Engineering Advanced Approach to Elementary Engineering Statics and Dynamics

    I already have a degree in physics. Is there a book that describes the applications for a person who knows the underlying physics? Poking around, I can only found 1000 page tomes that are also teaching the underlying physics. In the back of my head I am thinking about 1) Systems of wheels...
  41. Pipsqueakalchemist

    Engineering Dynamics rigid body homework question

    So I’m confused about a few things in the solution. Why is it that speed of the V_h appears on both gear a and b? Is it because both gears are both in contact so they have equal speeds just in opposite direction. Same confusion for V_e being on the top of gear b. So Just because gear e doesn’t...
  42. Pipsqueakalchemist

    Engineering Dynamics rigid body question -- Velocity of points on a car's wheel

    The solutions used the spend of the wheel and its radius to find the angular velocity. I’m confused because I thought to find angular velocity you use the speed at the points of the radius not the translation speed of the wheel itself. Can someone explain this to me please
  43. A

    A The exciton dynamics in the FMO complex

    I want to study the coherence transfer of the excitation in the FMO complex, so I have to solve the Lindblad master equation. Can I treat my system as a two level system?
  44. OmkarE11

    Error in ANSYS Explicit Dynamics

    I am tring to simulate impact of cricket ball on a bat. Whenever I try to simulate with custom materials it shows an error like 'Solver initialization failed. See the log file.' But when I carry out with steel as the material it works fine. Please help.
  45. Pipsqueakalchemist

    Engineering Dynamics help: Block on a wedge on an incline (frictionless surfaces)

    So I’m having trouble with relative motion with moving inclines and I literally can’t find any help online and my prof does a lot of these problems. This is one of my homework problems, can anyone help me with it please.
  46. P

    Conservation of energy in rotating bodies

    The conservation of energy equation is basically GPE is converted to KE of block and KE of cylinder. To get the correct answer, the KE of the cylinder is 1/2mv^2, where m is its mass and v is the velocity of its COM (which is the centre of cylinder). However, I viewed the cylinder as rotating...
  47. John Mohr

    Constant Circular Motion Not Really Constant

    I was pondering my practice of talking about circular motion in the horizontal direction and the vertical direction. But I'd often would see in books, notes, and the internet that we assume constant velocity for the vertical case. However, when one thinks about the forces at different points in...
  48. yucheng

    Incorrect derivation of tangential acceleration in polar coordinates

    I am trying to derive the tangential acceleration of a particle. We have tangential velocity, radius and angular velocity. $$v_{tangential}= \omega r$$ then by multiplication rule, $$\dot v_{tangential} = a_{tangential} = \dot \omega r + \omega \dot r$$ and $$a_{tangential} = \ddot \theta r +...
  49. C

    Can we unlock the mysteries of tectonic plate movement through geologic history?

    I have been trying to learn about the geology of the western United States since recently moving to New Mexico. There are many videos and articles on line that explain the present and the past both in terms of tectonic plate movements. But the ones I have looked at do not describe why tectonic...
  50. swiper122

    Fluid dynamics calculation -- Draining a barrel through a pipe

    v1- velocity of water at the top of the barrel v2- velocity of water at the the pipe (bottom of cylinder) p + (⍴ *(v1)^2)/2 + ⍴gh=p + (⍴ *(v2)^2)/2 + ⍴gh atmosferic pressure cancels out (⍴ *(v1)^2)/2 + ⍴gh = (⍴ *(v2)^2)/2 + ⍴gh density doesn't affect the result(cause its in every term)...
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