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. Odious Suspect

    Orbital dynamics: "The familiar arc-cosine form"

    This arises in Joos's discussion of planetary motion, at the following URL: https://books.google.com/books?id=wFl2MkpcY6kC&lpg=PP1&pg=PA91#v=onepage&q&f=false I've modified the notation in obvious ways. He asserts that the following expression is "the familiar arc-cosine form": $$-\int...
  2. T

    Find the time for the string to break

    Hi all! I am currently working on an assignment for my dynamics course in which we need to create our own "real world" problems. I chose to do a problem which would solve the time at which the string of a lanyard would break when it is swung in a circle. My problem is with my end numbers. They...
  3. Doney Felipe MEjia

    Can someone help me with an analytical dynamics exercise?

    At a certain instant, the velocity and acceleration of a particle ar defined by v= 3i + 4j - 6k m/s and a=-2i + 3k m/s2. Find the radius of curvature and change of speed of the particle at the instant.
  4. C

    Finding Velocity with Varying Force and Friction

    Homework Statement The 3kg collar is initially at rest and is acted upon a force Q which varies by the the graph shown. Knowing that the coefficient of kinetic friction is 0.25, determine the velocity of the collar at t = 1 s and t = 2s. Homework Equations FΔt = mΔv Ffriction = .25 x N The...
  5. C

    What is the power of an elevator?

    Homework Statement Homework Equations So I've been thinking about this one for a while and I've tried to read up about Power in general. I think Power = Work/ Time = (Force x Distance)/Time or Force x Speed. The Attempt at a Solution F = ma, so if velocity is constant, a = 0. So that would...
  6. jdawg

    Dynamics: Time taken for Block A to slide on Block B

    Homework Statement Find the time it takes for block A to slide 0.5m on block B. Mass A=10 kg Mass B=35 kg I included a screen shot from my online homework. Homework Equations FR=FNμkThe Attempt at a Solution For Block A: mAa=T-FRA-WAsin(30) T=10a+68.67 For Block B: FRC=(mAg+mBg)μBC FRA=mAgμAB...
  7. ChrisVer

    Strong Flavor Dynamics for tops questions

    I was reading through this paper: A Model for Strong Flavor Dynamics for the Top Quark Ehab Malkawi, Tim Tait, C.--P. Yuan It's pretty old, so maybe some things might have changed... I have two questions. Q1: I quote from abstract: and from intro Were (or are) the measurments that showed the...
  8. P

    What is the driving resistance force?

    Hi, I'm doing a study about tire dynamics and have some question that I can't get answers to. The first images shows the forces balances. Since we have no turqe the force has to balance ant the extensence of the T_r is obvious...
  9. sa1988

    Fluid dynamics, solving ODE to find particle path

    Homework Statement A time-dependent two-dimensional fluid flow is given, in a Cartesian coordinates system (x, y), by the velocity field: u = (y, t-x) Show that, at time t = 0, the streamlines of this flow are circles centred on the origin. Find equation of the streamline that passes through...
  10. S

    Fluid Dynamics - Pressure at the end of a syringe

    Hello there Physics Forum! This is my first post here. This problem has been boggling me all day and I'm need of help in piecing together what I've come up with so far. I'm currently working on a personal project related to paint spraying. In this project I'm using a syringe & needle to feed...
  11. C

    Displacement from an Acceleration Time Graph

    Homework Statement Homework Equations Kinematic equations t = 18s when the velocity is back to 54km/h or 15m/s at t = 2, V = 13.3 m/s at t = 4.5, velocity is 1.5 m/s at t = 1, V = 15m/s The Attempt at a Solution I have solved the first part and I have the time at which it is 54km/h again, but...
  12. A

    Curvilinear Motion: Polar Coordinates (Engineering Dynamics)

    Homework Statement Homework EquationsThe Attempt at a Solution I have stared at this for hours and don't know where to start. I think I need to get r in terms of t but I don't really know how with the information given. I just need a good hint to get started.
  13. C

    Find Tangential Component of Acceleration and Curvature

    Homework Statement Homework Equations I know that the tangential accel is v = wr and that Centripetal = v^2/r The Attempt at a Solution For A, I thought it would be straight forward if I had the radius as well as omega. I know that the distance between A and B is 60in, but I don't think it...
  14. C

    Find the largest initial velocity

    Homework Statement Homework Equations I know that this could be solved through kinematics. The Attempt at a Solution I thought that I could use the range equation to solve for Vo, but since there is an initial height, I don't think that could work. I thought that maybe I could use the...
  15. C

    Determine the angular speed theta_dot

    Homework Statement Homework Equations Vθ = r x θdot Vr = rdot Accelθ = r ⋅ θdot^2 + 2(r dot)(theta dot) Accelr = r double dot - (r ⋅(θdot)^2) The Attempt at a Solution I know that the answer is supposed to be But I'm not quite sure on how I'm supposed to get to an answer like that. I'm...
  16. C

    Velocity and Acceleration Vectors

    Homework Statement Homework Equations Rotational Kinematic Equations Kinematic Equations The Attempt at a Solution I honestly have no clue how to get a vector out of this. I thought about an equation: Θ = Θ(initial) + ω(initial)*t + .5αt^2 and how maybe that v = wr could play into this...
  17. S

    Is a Vertically Hung Spring Mass System SHM?

    In an SHM, the only force that should be acting, that is the net force should be the restoring force F, by definition... F = -kx For example there is a massless spring of spring constant k attached to the ceiling and there is a body of mass m hung at it and avoiding all kinds of friction...
  18. S

    Spring Constant in Hooke's Law

    How does one arrive at the following equation to approximate spring constant for solids... using Hooke's Law F ∝-x ⇒ F = -kx and strain∝stress ? k = (m/a2) × (K/ρ)½ where k≡spring constant m ≡ mass of a single atom a ≡ atomic spacing K ≡ bulk modulus ρ ≡ density
  19. S

    Equation for Simple Harmonic Motion?

    In Simple Harmonic Motion, can (k/m) = ω2 be expressed for all SHMs or only the ones in which the mass due to which the SHM is being executed is performing a circular motion? Since for example, in the case of spring, there is no circular motion involved, so omega should not be defined for...
  20. K

    Engineering Book on Dynamics (Mechanical systems)

    I'm looking for a book that has problems and explanations (not necessarily background theory) about mechanical systems. Consider the picture below for reference. The idea is I want to get a hold of energy and impulse methods for solving problems like this, eventually the book would have a...
  21. C

    Find Velocity and Time from an Acceleration vs Time Graph

    Homework Statement The rocket car is subjected to a constant acceleration of Ac = 6 m/s^2 until T1 = 15 s. The brakes are then applied which causes a deceleration at the rate shown until the car stops. Determine the maximum speed of the car and the time T when the car stops. Homework Equations...
  22. **Mariam**

    Solving MCQ Total Energy: Question 8 - Guide & Key

    Homework Statement Question 8 how do we solve it? Homework EquationsThe Attempt at a Solution I thought it was B but i don't have a key or any guide. This book was used and the answer written by the previous book user was C. Why?
  23. J

    Radial acceleration of a particle in a groove on a turntable

    Homework Statement A horizontal turntable rotates at a constant rate ω about a fixed vertical axis through its center O. A particle of mass m can slide in a fictionless circular groove of radius r centered at O' which is r/3 from O. What is the radial acceleration of m in direction O'm...
  24. J

    Visualizing Decoherence in a Momentum Basis

    Can you describe or how does one visualize a decoherence branch where the position basis is not preferred (copenhangen, bohmian) but momentum basis (as say one of the Everett). Or if a world has position basis disallowed (suppressed for sake of discussion) and it's all momentum basis.. would...
  25. denisaf

    Laws of Mass Dynamics: Conservation & Transformation

    The laws of thermodynamics deal with the irreversible flow of energy. Conservation of energy is the first law and increasing entropy (disorder) in an energy flow is the second. The conservation of mass is the equivalent first law for matter. It is commonly recognized. But what about the...
  26. B

    Special Relativity - Dynamics -- Traveling in Space

    Homework Statement [/B] Assume that 437 days is a reasonable limit for how long a human can endure constant-velocity space travel. Proxima Centauri, the star closest to our Sun, is 4.24 light years away from Earth. If you wanted to fly to Proxima Centauri within the 437-day limit in a rocket...
  27. B

    Special Relativity -- Dynamics -- Energy

    Homework Statement Antihydrogen is the only antimatter element that has been produced in the laboratory, albeit just a few atoms at a time. Each antihydrogen atom consists of a positron in orbit around an antiproton and has the same atomic mass as hydrogen. If an antihydrogen atom collides with...
  28. vetgirl1990

    Fluid dynamics: Initial velocity of milk outflow from carton

    Homework Statement A hole is punched in a full milk carton, 10cm below the top. What's the initial velocity of outflow? Homework Equations P2 = P1 + ρgh Conservation of energy of fluids: P2 + 1/2ρv22 + ρgy2 = P1 + 1/2ρv12 + ρgy1 The Attempt at a Solution Set the top of the carton as P1, and...
  29. W

    Sun Orbits Center of Mass w/ Jupiter & Earth: How To Calculate?

    I know that if I have a two-body system, the sun and the earth, then the common centre of mass is orbited every 365 days. What about if I add another planet in, say jupiter? Does the sun still orbit the centre of mass every 365 days? With two bodies, their orbital period about the centre of mass...
  30. Dusty912

    How do I solve for rotational dynamics using Newton's second law?

    Homework Statement I attached the stated questions. Mainly need help with question 2. See below for my answer to question 1.Homework Equations ΣT=Iα ΣF=ma moment of inertia of sphere: I=(2mR^2)/5 moment of inertia of disk: I=(mr^2)/2 v=rω V(center of mas)=V(tangential) -because of smooth...
  31. dwdoyle8854

    Classical Dynamics -- Falling chain and energy conservation

    Homework Statement The statement of the question is:A chain of uniform linear mass density ##\rho##, length ##b## and mass ##M## hands as shown in the figure below. At time t=0, the ends A and B are adjacent, but end B is released. Find the tension in the chain at point A after end B has...
  32. W

    How Do You Calculate Orbital Dynamics in a Simple Java Simulation?

    I'm an undergrad (so my simulation is VERY simple), writing a java program to simulate the solar system. And I'm a bit stuck on how to calculate a couple of important things. I'm literally right at the start of this, with just a sun and an earth. Initially I had my Earth going round my...
  33. G

    Possible to derive pendulum velocity in a dynamic approach?

    Hi, Using conservation of energy $$m\cdot\ g\cdot\left(h_0-h\right)=\frac{1}{2}m\cdot\ v^2$$ it's easy to find the exact velocity of a pendulum $$v\left(h\right)=\sqrt{2g\cdot\left(h_0-h\right)}$$ at height ##h## above the minimum when it was let go from the inital height ##h_0##. Is it...
  34. vetgirl1990

    Kinematics of a falling object to hit target

    Homework Statement An airplane flies horizontally with a speed of 300m/s at an altitude of 300m. Assume the ground is level. At what horizontal distance from a target must the pilot release a bomb as to hit the target? Answer: 2.7km Homework Equations a=v/t=d/t2 r_f = r_i + v_i*t + 1/2at2...
  35. C

    Why are the variables different in Hibbeler's Dynamics?

    I am currently in a college dynamics class, and we are discussing energy and work. In other classes(calculus or physics), we have represented work, potential energy, and kinetic energy with the variables W, K, and U (respectively). However, in my dynamics book, these are represented using the...
  36. L

    Fluid Dynamics - Hydrostatic Pressure #2

    Homework Statement a Flat rectangular door in a mine is submerged from one side in water. The door dimensions are 2m high, 1m wide and the water level is 1.5m higher than the top of the door. The door has two hinges on the vertical edge, 160mm from each corner and a sliding bolt on the other...
  37. L

    Fluid Dynamics - Hydrostatic Pressure

    Homework Statement A rectangular vertical plate is submerged in water. The top edge is horizontal and at a depth of 0.6m. The length of the vertical edge is 1.2m. determine at what dept under the water surface a horizontal line can be drawn on the plate such that the hydrostatic forces on...
  38. H

    What is VigLink and How Does it Affect Links on Physicsforums?

    I am failing to understand Dirac's constraint dynamics. Can anyone suggest a useful resource? Thanks
  39. D

    How Does Non-Pure Rolling Differ from Pure Rolling in Rotational Dynamics?

    Question: Refer to https://www.physicsforums.com/threads/rolling-motion-of-plank-and-cylinders.93329/ I am able to understand all the points until the point v_roller+rω=v_plank. I have a tough time understanding this part. My attempt at the question: I think that the static friction at the top...
  40. C

    Year 1 physics: Fluid Dynamics with Tree Sap replacing Water

    Homework Statement A tree loses water to the air by the process of transpiration at the rate of 110 g/h. This water is replaced by the upward flow of sap through vessels in the trunk. If the trunk contains 1900 vessels, each 100 μm in diameter, what is the upward speed of the sap in each...
  41. B

    Dynamics - Pulley System with Rotating Rod

    Homework Statement At the instant shown, the rod R is rotating about its centre of rotation with ω=3.8rad/s. mA=10kg; The pulley, with mP=8.7kg and RP=0.2m, may be modeled as a uniform disc. The rod, with mR=4.1kg and L=0.8m, may be modeled as a thin beam rotating about one end. g=9.8m/s ²...
  42. L

    Problem 2 rigid rods - Greenwood - Classical Dynamics

    From "Greenwood Donald T. - Classical Dynamics", Chapter 1, Section 1-4 (virtual work), Example 1-4: https://books.google.it/books?id=x7rj83I98yMC&lpg=PP1&hl=it&pg=PA26#v=onepage&q&f=false 1) There are 3 mass points of the same mass m moving on a plane (even if the text doesn't specify this)...
  43. SquidgyGuff

    Finding relativistic force in terms of acceleration

    Homework Statement The instantaneous force F acting on a particle, as measured in frame S, is Use the formula for the linear momentum () in and the definition of the acceleration a to show that The Attempt at a Solution The professor said that this required use of programs such...
  44. Kushwoho44

    Fluid Dynamics: Static Thrust on a Conv-Div Nozzle

    Homework Statement The attempt at a solution Hi all, I am tasked with finding the static thrust generated by this convergent-divergent nozzle. The stagnation pressure is known the inlet. Now, personally, I would've thought drawn a control volume around the entire nozzle. And then said...
  45. Buzz Bloom

    Orbit Dynamics in an Expanding Universe

    After learning a bit from the thread "The Dark Sky Ahead", I have tried to think through the dynamics of gravitational interactions in a simplified scenario. Unfortunately the GR math of the problem is over my head. My attempt below, using a simpler approach, leaves me quite confused. If my...
  46. F

    Fluid Dynamics: Static pressure in compressible Liquids

    Homework Statement [/B] "Derive a relation between the static pressure P at a point and its depth y from the free surface of the liquid. Given the surface density of liquid is ρο, and compressibility of the liquid is k." Homework Equations ##ρ(P) = ρ_οe^{kP}## ##dP = ρg dy## The Attempt at a...
  47. P

    What is the new Hamiltonian constraint operator for loop quantum gravity?

    A critique of LQG here: "The next step in the construction of LQG is to decide what the dynamics are. Technically, this is done either (A) by choosing a "Hamiltonian constraint" in parallel with the Hamiltonian formulation of GR, or (B) in the spin-foam formalism, by postulating some sort of...
  48. J

    Struggling to Understand Pulley System Dynamics

    Homework Statement it is Problem 3.30. Homework Equations I am not sure how to sum the forces about each consecutive pulley I have been at this for 4 hours now. It is sad I can solve the DE questions and not this. The Attempt at a Solution I had the first pulley at the top as (where y is...
  49. S

    Modified Newtonian Dynamics vs. Quantum Gravity

    OK. I'm sure this is probably been considered before but it is my musings coming off a recent attempt to photograph the Andromeda Galaxy. I did a few two minutes or so shots of Andromeda and stacked them for a total of about 14 minutes. Fairly nice. There is some structure to be seen but...
  50. upender singh

    Stiffness constant of a spring

    1:question A weight W is suspended from a rigid support by a hard spring with stiffness constant k . The spring is enclosed in a hard plastic sleeve, which prevents horizontal motion, but allows vertical oscillations. A simple pendulum of length l with a bob of mass m (mg<<W) is suspended from...
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