What is Dynamics: Definition and 1000 Discussions

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. 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...
  2. 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 /...
  3. 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...
  4. 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?
  5. 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...
  6. 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...
  7. 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...
  8. 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...
  9. 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...
  10. 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...
  11. F

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

    Any book on many body Newtonian dynamics?
  12. 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...
  13. 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...
  14. 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...
  15. 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...
  16. 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...
  17. 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...
  18. Angelo Pascal

    Geophysics: Fluid Dynamics Problem

    (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) +...
  19. 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.
  20. 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.
  21. 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...
  22. 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...
  23. 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...
  24. 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...
  25. 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...
  26. 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.
  27. 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?
  28. 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...
  29. 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...
  30. 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...
  31. 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...
  32. 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...
  33. 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
  34. 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?
  35. 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.
  36. 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.
  37. 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...
  38. 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...
  39. 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 +...
  40. 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...
  41. 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)...
  42. Shankar Das

    Practicing Mechanical Engineering Dynamics Problems

    Hello, I hope you all are doing fine and healthy. For my mechanical engineering dynamics I want to practice related problems taught in my class, here is a preview of some problems. Can anyone tell me from which book or solution manual are these problems from? I want to practice as much problems...
  43. A

    What is the Residual in Computational Fluid Dynamics?

    Can someone please tell me a basic and easy-to-understand example of Residual in CFD? Thank you
  44. jedishrfu

    News Some of My Friends Having Fun (Boston Dynamics Doing the Twist)

  45. K

    Which Program for Drawing Statics & Dynamics Mechanicals and Setting Dimensions?

    Wich The Program (Software) Using To Draw Statics And Dynamics Mechanichal Same This 100% When Create This below Which Program Using ? And set Dimensions Thanks For All
  46. Rzbs

    I Semiclassical model of electron dynamics

    Why do we exclude interband transitions in semiclassical model of electton dynamics? I mean why it is an assumption in this model?
  47. ezfzx

    Ball rolling within a rolling cylinder

    Cylinders rolling down inclines are a common demo. But how do you model the movement of a sphere rolling within a rolling cylinder? I teaching a physics class and this question came up and my dynamics math is a little rusty. But I haven't found anything like this in any book or online. There's...
  48. E

    Two rotating masses balanced by a third mass (rotational dynamics)

    Here's a diagram of what the system looks like: So far I have figured out what the initial angular velocity is, if the system is balanced (no movement): ## \sum F_m = m*\frac{v^2}{R_0}-\frac{Mg}{2}=0 ## ##m \frac{v^2}{R_0}-\frac{Mg}{2}=0 ## divide both sides by m ##\omega_0 =...
  49. yecko

    Why is ro = 0.2255 in fluid dynamics vortices?

    why is ro = 0.2255? Thank you
  50. T

    Calculating air resistance for a cart rolling down a ramp

    I am doing a physics lab where we are supposed to calculate air resistance and find the impacts of velocity and cross sectional area on air resistance. For the experiment, we rolled a cart down a ramp and measured data using Pasco Capstone software. When rolling the cart down the ramp, we...
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