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. R

    What Is the Horizontal Force Between the Truck Tires and Ground?

    1. Problem statement: A 5000-lb truck is being used to lift a 1000-lb boulder B that is on a 200-lb pallet. Knowing the acceleration of the truck is 1 ft/s^2, determine the horizontal force between the tires and ground. The truck is on a horizontal plane with the boulder and pallet...
  2. F

    Calculating Minor Head Losses in a Fluid System

    I have a question where I have to find minor head losses for a system using both the equivalent length method and number of velocity heads method . It will not let me attatch the drawing here but , a liquid is to be pumped from an underground vessel (which is vented) to a pressurissed...
  3. C

    Engineering Dynamics - Car Striking a Barrier

    Homework Statement A car, assumed to be rigid and having a mass of 800 kg, strikes a barrel-barrier installation without the driver applying the brakes. From experiments the magnitude of the force of resistance F_r, created by deforming the barrels successive, is shown as a function of the...
  4. J

    Use of Trotter Theorem in Path Integral Molecular Dynamics

    I am unable to prove step 8.3 in this proof of the path integral formulation of molecular dynamics https://files.nyu.edu/mt33/public/jpc_feat/node11.html Any help would be much appreciated.
  5. W

    Best books for Vector Mechanics: Statics and/or Dynamics

    Between Beer and Hibbeler, which is the better book? Are there any other books beside those two that are any good? Are there any books that I can use to complement either of these two to get a more theoretical understanding of are they fine alone? Thanks
  6. C

    Fluid dynamics - find distribution of a conserved variable

    I accidentally posted this to the "Calculus & Beyond" forum when I meant to post it to the physics forum. If someone can tell me how to move this post, I will get rid of it here! Homework Statement Consider a property, for example temperature θ, that is conserved during advection (i.e. Dθ/Dt =...
  7. D

    Dynamics class w/o kinematics equations?

    Homework Statement My problem is I don't understand what my professor wants us to do instead. He says that we don't need to memorize any equations, namely the equations of motion, and that everything can be solved with basic principles and integration. The problem is, I have no idea how to...
  8. L

    Rotational Dynamics Homework: Velocity & Acceleration of Wheel

    Homework Statement A wheel is spinning at n=1200rpm. The wheel starts to linearly decelerate, and after t=100s it stops. Determine the velocity, and acceleration of a point 10cm from the center of the mass, after 50 seconds of decelerating. The radius of the wheel is 30cm.Homework Equations...
  9. F

    Calculating Minor Head Losses for Pumped Liquid System | Fluid Dynamics Question

    I have a question where I have to find minor head losses for a system using both the equivalent length method and number of velocity heads method . It will not let me attatch the drawing here but , a liquid is to be pumped from an underground vessel (which is vented) to a pressurissed...
  10. G

    Optics and fluid dynamics simulation software

    I am doing "Schlieren imaging" visualization of a gas flow from the nozzle. could anyone please recommend a software to simulate a gas flow from the nozzle. in addition please recommend a software to simulate optics, like the propagation of a light beam through the optics and image...
  11. S

    Molecular dynamics help - Lennard Jones potention

    Homework Statement The Lennard-Jones potential function u(r) = 4ε[(σ/r)^12 - (σ/r)^6] If intermolecular interactions are ignored in this calculation for r > rc , show that in the mean field approximation in the long range correction [itex] P*LR to the measured pressure is given by...
  12. B

    What's the Next Good Book to Learn About Nonlinear Dynamics?

    I completed the book 'Nonlinear Dynamics and Chaos' by Strogatz. What will be next good book to learn about nonlinear dynamics?
  13. F

    Fluid Dynamics Question - Pressure Difference in Horizontal Pipe

    Homework Statement The Trans-Alaska Pipeline System (TAPS) carries around 100,000m3 of oil per day from the Northern Alaskan oil fields to the nearest ice-free port of Valdez, around 1300km away. The pipe has an outer diameter of 1.22m and a wall thickness of 12mm. Eleven pumping stations...
  14. J

    Complete positivity and quantum dynamics

    Hi again, Another, possibly trivial, question. In quantum dynamics we consider maps containing the evolution of a system. Suppose we have a completely positive (CP henceforth) map (1) \Gamma:\mathcal{M}_k\rightarrow \mathcal{M}_n This map has following properties: Trace-preserving Complex...
  15. Y

    Comoving Dynamics: Overcoming STR for >c Recessional Velocities

    Conventional Cosmology would explain greater than c recessional velocities of the nebula as a non-problem regarding STR because the luminous matter is co-moving with respect to local space rather than with respect to local space (the latter generally referred to as peculiar motion). In an...
  16. R

    Parabolic track dynamics + calculus (Hard)

    Homework Statement The problem is in the photo below: https://www.physicsforums.com/attachment.php?attachmentid=71928&stc=1&d=1407288108 Text: Figure CP6.74 shows an accelerometer, a device for measuring the horizontal acceleration of cars and airplanes. A ball is free to roll on a parabolic...
  17. R

    How Do You Prove the Equation and Find the Block’s Speed at Position L?

    Homework Statement A block of mass m is at rest at the origin at t = 0. It is pushed with constant force Fo from x = 0 to x = L across a horizontal surface whose coefficient of kinetic friction is μk = μ0(1 - x/L). That is, the coefficient of friction decreases from μ0 at x = 0 to zero...
  18. S

    Good book on particle dynamics

    I am a B.Sc. 2nd year student of Maths (Honours-equivalent to an US Maths Major), Physics and Computer Science(Probably equivalent to US Physics minor and CS minor) in a college in India. I hope to become a specialist in Mathematical Physics later on. Since my background knowledge of core...
  19. B

    Engineering Dynamics, weight is missing, simple problem

    Homework Statement It is given in the photo Homework Equations They are all given in the photo The Attempt at a SolutionI solved exactly the same as in the solution manual, except for the FBD of the slider B, when they write the 2nd Law, they do not input the weight there, only the...
  20. I

    MHB Integration and population dynamics?

    can someone explain this problem step by step (not a homework problem, just an example i found and i want to see how its done). a hot wet summer is causing a mosquito population explosion in a lake resort area. the number of mosquitoes is increasing at an estimated rate of 2200+10e^(0.8t) per...
  21. A

    Conv-Div nozzle and Fanno flow (Gas Dynamics)

    Homework Statement A rocket nozzle is operating with a stretched out throat, (L = 50 cm and D = 10 cm). If the inlet stagnation conditions are po1 = 1 MPa and To1 = 1500 K, determine the nozzle exit velocity and mass flow for a back pressure of 30 kPa. The diameter of the nozzle at the exit...
  22. H

    Structural Dynamics Analysis - Modal method or time integration?

    Hi all, I need help with numerical solution of motion equation. From the numerical point of view and in the real of the finite element method, which method is recommended for the solution of damped ( proportional damping) linear motion equation? I have been trying three common methods; Modal...
  23. J

    Dynamics of a system of particles all influencing eachother

    Take a closed system of particles. Each has it's own mass, but that's really about it for the sakes of this argument. Now suppose there is some standard force law that applies between particles, whatever it may be. (In general it will depend only on the separation between particles and thus be...
  24. V

    Rotational Dynamics: Hoop Rolling without Bouncing

    Homework Statement A small body A is fixed to the inside of a thin rigid hoop of radius R and mass equal to that of the body A. The hoop rolls without slipping over a horizontal plane; at the moments when the body A gets into the lower position, the center of the hoop moves with velocity v0...
  25. A

    Dynamics: Normal and Tangential projectile motion problem

    Homework Statement A canon fires a projectile at a speed of 100 m/s at angle of 20 degrees. (a) what is the radius of curvature of the projectile at its highest altitude? (b) What is the radius of curvature of the path .5 seconds after firing? Homework Equations Velocity vector = s'ur...
  26. B

    Mastering Dynamics: Tips and Advice for Passing with Flying Colors

    Hello everybody, Last semester I took dynamics and I got FD, and luckily the course is going to open in the summer school too.So I am trying to pass the course in the summer school, why not getting a good grade too. Reasons why I did not pass were mainly because I did not like the teacher (...
  27. ion santra

    Nonlinear Dynamics Models for Undergrad Research

    Can anybody suggest some basic models or problems in non linear dynamics on which an undergrad student can work on.
  28. J

    Confusing points in relativistic dynamics

    Hi everyone: I just started to learn special relativity but totally being confused about "velocity", "momentum" and "force". 1. The relativistic momentum is defined by "rest mass * ordinary velocity * gamma". There are 2 kind of explanations. The first one is combining "rest mass * gamma"...
  29. J

    Cylinder attached to a block on an inclined plane, rotational dynamics

    Homework Statement A cylinder of mass M and radius R, with moment of inertia: I_c = \frac{1}{2}MR^2 rolls down without slipping through an inclined plane with an angle of θ, while pulling a block of mass Mb with an attached frame (of insignificant mass) which is connected to the axis of...
  30. Z

    Need help for a CFD(computational fluid dynamics) software

    My friend is trying to reproduce a research paper calculated using the CFD(computational fluid dynamics) software package star-CD sold by CD-adapco, but so far he failed, what can he do? Here is the paper he is trying to reproduce: Endothelial Cell Layer Subjected to Impinging Flow Mimicking...
  31. J

    Blocks and pulley with mass - rotational dynamics

    Homework Statement Two blocks of masses m1 = 8.00 kg and m2 = 12.00 kg are connected by a string of insignificant mass. The string lies on a cylinder of mass 0.50 kg and a radius of 0.15 m. The coefficient of kinetic friction between m1 and the surface of an inclined plane is 0.10. The angle...
  32. R

    Rotating motor dynamics: reactions on supports.

    Homework Statement Hi everyone! I'm struggling to understand how to solve this problem, I searched on the web, but I didn't find anything similar. I have a motor delivering a power P=5kW at n=1500rpm. This motor is mounted on 4 supports, each having a rigidity k=15kN/m. I know that distance...
  33. R

    How can I accurately calculate the required motive gas rate for an ejector?

    Does anyone have a good reference to calculate an ejectors required motive gas rate. As I understand it the pressure of the motive gas out of the nozzle and the pressure of the process gas are the same. A mass/volume flow can be guessed and the properties on the inlet can be calculated using...
  34. B

    How Should You Properly Ask for Homework Help in Online Forums?

    https://scontent-b-sjc.xx.fbcdn.net/hphotos-xap1/t1.0-9/10373973_306663899490733_8092061444466097264_n.jpg
  35. A

    Question in dynamics projectile motion

    Attempt solution Y=(vsinø)t-0.5gt^2 4=(vsinø)t-4,9t^2 But there is 3 variables! Another eq is X=(vcosø)t 6=(vcosø)t But i did not found any away to solution
  36. J

    Rotational Dynamics and string Tension

    Homework Statement A light string is wrapped around a solid cylinder and a 300g mass hangs from the free end of the string. when released, the mass falls a distance of 54cm in 3.0s. a) Calculate the tension in the string. b) Calculate the mass of the cylinder. Homework Equations...
  37. A

    Mistake in Dynamics Circular Problem's Solution

    Please look at pictures. I do not understand the solutions; Here is how I find length of string: 5m/s*1.2s/rev=6m/rev=circumference=2piR R=0.95m. For the force: T=mv^2/r= 0.350 kg *5^2/0.95= 9.21N They got 9.16N?
  38. G

    How Long Does It Take for a Water Droplet to Move Radially on a Turbine?

    Homework Statement A water droplet condenses at r0=0.80 m. The turbine is rotating at a fixed speed of N RPM. You can treat the water droplet as a point mass of m=0.002 kg. Starting from rest at its formation point, it starts moving outward on the radial vane as shown. Its mass stays...
  39. A

    Is This the Solution? A Review of Dynamics Pushing Blocks with Visuals

    Please look at pictures. Weirdly, my textbook does not give the answer to this question. Can you check my answer? Sorry for the really bad writing. If you ask, I can more clearly write it.
  40. J

    Cosmic Dynamics - Cosmological Constant

    Suppose the energy density of the cosmological constant is equal to the present critical density ε\Lambda = εc,0 = 5200 MeV m-3. What is the total energy of the cosmological constant within a sphere 1 AU in radius? My answer: ε\Lambda = ET / V ET = ε\Lambda * V = (8.33 * 10-10...
  41. A

    How Do Different Techniques Stop an Airplane on a Ship's Short Airstrip?

    A ship, on which airplanes land, has an airstrip of 70 m. The ship uses three different techniques to stop airplanes when they are landing. The first technique is to use a cable reel of radius 0.4 m, around which a non-elastic rope is coiled. The reel is to be rotated about its axle - which is a...
  42. G

    Dynamics question: Angular Velocity/kinematics

    A piece of stone of mass m is rotating at constant angular speed ω in the vertical plane about the point O as shown in the figure. A rope of length R connects the ball to O. If the rope breaks when the stone is at A, calculate how long it takes before the stone falls back to the same level...
  43. C

    Dynamics of a Cord: Solving Tension for Arlene

    Homework Statement Arlene is to walk across a “high wire” strung horizontally between two buildings 10.0 m apart. The sag in the rope when she is at the midpoint is 10.0°, as shown in Fig. 4–47. If her mass is 50.0 kg, what is the tension in the rope at this point?Homework Equations The...
  44. crador

    Fluid Dynamics pipeline with a venturi injector

    Hey guys, I've been wracking my brain for a while, and thus I have landed here yet again. My problem is the following: Say you have a pipeline with a venturi injector, and intermittently a large tank of water with a portion of air on top -- I.e. a closed circuit communicating between the...
  45. mattyboson12

    Understanding Bernoulli's Equation for Fluid Dynamics with Electric Pumps

    Hi, am having a few problems applying bernoulli's equation when an electric pump is involved. I have attached a picture of the question. I understand how to apply bernoullis for venturi and pitot tubes but when it involves work being done on the system eg. a water pump, fan exhaust I don't know...
  46. O

    Troubleshooting System Dynamics Problems - Expert Help Needed!"

    Hi folks! My system dynamics teacher gave us a couple of assignments to work out, there is one though that I can't seem to work out properly. Now I am aware that this is maybe not the correct part of the forum, but I didn't know where else to put it. I would love to see one of you guys...
  47. C

    Get Quick Answers to Your Dynamics Questions | No Edit Needed"

    Edit: Nevermind
  48. K

    Analogy between fluid dynamics and electromagnetism

    I've recently heard of an analogy between fluid dynamics and electromagnetism in which the velocity flow field is identified with the magnetic vector potential, (and therefore the vorticity is identified with the magnetic field), and the vector \omega \times v is identified with the electric...
  49. V

    Angular Acceleration of A rod with friction. Dynamics (General Plane)

    Homework Statement A 100 kg slender rod is lifted on the left end until the angle between the ground and the right end is 30 degrees. The right end is still in contact with the ground. The coefficient of friction between the rod and the ground is .5 and the length of the rod is 2.1 m...
  50. B

    Fluid dynamics in horizontal pipe

    There's a figure that comes with the question but I'm having trouble attaching it so I will describe it the best I can. There is a large cylinder labeled the reservoir. A horizontal pipe is connected near the base of the reservoir and it is open at the other end so fluid flows out (point B)...
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