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. B

    When will the football players collide?

    Homework Statement Two football players separated by 42m run directly toward each other. Football player 1 starts from rest and accelerates at 2.4m/s^2, and football player 2 moves uniformly at 5.4m/s. How long does it take for the players to collide? Given: player 1: v1=0m/s, a=2.4m/s^2Player...
  2. Nile Anderson

    Relationship between Velocity, Kinetic Energy and Mass

    Homework Statement Homework Equations i) F=ma=mv/t ii) E=mv2/2 The Attempt at a Solution Now based on equation 1 , I have concluded that the velocity gained is inversely proportional to m, and that so is the kinetic energy , I have seen otherwise.[/B]
  3. U

    How many constants-of-motion for a given Hamiltonian?

    I am using Jose & Saletan's "Classical Dynamics", where they introduce a rather contrived Hamiltonian in the problem set: H(q_1,p_1,q_2,p_2) = q_1p_1-q_2p_2 - aq_1^2 + bq_2^2 where a and b are constants. This Hamiltonian has several constants-of-motion, including f = q1q2, as can be easily...
  4. M

    How did Newton come up w/ 1st law? Why does friction exist?

    So I'm trying to understand Newton's laws, and I know that friction is supposed to be the force that stops an object in movement. But I don't really understand why this is the case, as the force of friction is not something that can be perceived intuitively (unlike, for example, the force I...
  5. D

    Dynamics of Rotational Motion and hinge

    One end of a thin, uniform rod is connected to a frictionless hinge as shown in Figure 1. The rod has a length of 0.8 mand a mass of 2 kg. It is held up in the horizontal position (θ=90∘) and then released. 1)Calculate the angular velocity of the rod at θ=90∘. 2)Calculate the angular...
  6. Trent21

    Aerodynamics and general dynamics knowledge requirements.

    Long story short. Want to know waaaay before I get deep into Aerospace Engineering, what I need to know to do it and if I can, I've already retrieved books on it. Like Fundamentals Of Aerodynamics... Some Calc 2 books.. Calc 1.. etc etc. However I look at Calc 1/2, then look at my Aerodynamics...
  7. I

    How does the change in area affect the velocity of helium gas in a vacuum?

    Hello here is a schematic of the problem: http://imgur.com/CgcybVT A stream of helium gas will be used to carry aerosolized particles. I am assuming conservation of mass (and mass flow) The mission is to find the exit stream velocity of the gas. For the time being, i am assuming the weight...
  8. faradayscat

    How Does Air Pressure Affect Fluid Levels in a U-Shaped Tube?

    Homework Statement [/B] Suppose we have a u-shaped tube filled with water, with oil added at one end which disturbs the equilibrium. Now say one end is blocked off and the other is exposed to air flow which reduces the pressure above the water and causes the water to climb back to equilibrium...
  9. W

    Understanding solution method for finding accelerations in a mechanical linkage

    Homework Statement I was checking my work and Chegg uses the equations differently. Can somebody tell me why? Maybe I'm misunderstanding how/why to use the equation I chose. Homework Equations They say aB = -ω2ABRB/Ai I used aB = aA + αk x r - ω2rB/A The Attempt at a Solution So obviously...
  10. RoboNerd

    Calculating Moment of Inertia for Rotating Objects: A Kinetic Energy Problem

    Homework Statement What is the moment of inertia of a spinning object of radius 0.5 m and mass 6 kg moving at 5 m/s, if it has a kinetic energy of 100 J? 1) 1 kgm22) 2 kgm23) 4 kgm24) 8 kgm25) 20 kgm2 Homework Equations K.E. = Kinetic energy of rotation + kinetic energy of...
  11. W

    Finding the Angle of a Bar PQ using Geometry and Theta

    Homework Statement Homework Equations I want to say I should be using this one: aA = aB + α x rA/B + ω x (ω x rA/B) The Attempt at a Solution The only problem is that if I'm supposed to find the angular acceleration then i'd have to take the... inverse of the cross product? To get it back...
  12. Sahil Kukreja

    Rotational Dynamics Pulley Problem Help needed

    1.) Homework Statement A Pulley System is shown below Find the accelerations of m1, m2 and m3 (such that there is no slipping between the disk and the rope.) Assume the threads to be massless. Homework Equations The Relevant equations i think are Newtons 2nd...
  13. Umair Shariff

    Fluid Dynamics: Orthostatic Blood Pressure Equation

    Hi everyone, I have been hunting all over the Internet for an explanation to changes in the blood pressure when sitting, standing or lying down. I know the complex mechanisms that are involved but I need an equation for an ideal system with the heart in the middle and the pressure that needs to...
  14. S

    Is the Hamiltonian of a string given by a sum of harmonic oscillators?

    Homework Statement This problem is a continuation of the problem I posted in this thread: https://www.physicsforums.com/threads/equation-of-motion-from-a-lagrangian.867784/ (We have set the mass per unit length in that question to ##\sigma## = 1 to simplify some of the formulae a little.)...
  15. K

    Calculating the error in <x^2> from the error in <x> (Molecular Dynamics)

    Hi, does anyone know of an easy way to calculate the error in <x^2> from the error in <x>? I am running a molecular dynamics simulation and trying to work out the error in the fluctuation of kinetic energy <dEk> = <3/2NT^2> - <3/2NT>^2 from the error in <T>. Thanks in advance
  16. malaxtom

    Particle dynamics applied to geometrically parametric line

    I have an odd, yet intriguing question. I want to describe a particle that is constrained to move along a straight line in the x direction. The location of the particle can be described with theoretically infinite parametric parameters, d, along the line. For example: R = [d 0 0]T R = [d2 0 0]T...
  17. debajyoti datta

    Other Best book for nonlinear dynamics for a beginner

    What would be the best book for me if I want to learn nonlinear dynamics ? I have my basics clear in linear differential equations, linear system theory, integral transforms and random process if they suffice as prerequisites.
  18. F

    [Rotational dynamics] cube sliding on a dish

    1. Homework Statement A small cube is sliding on a round dish (see attached figure) . The cube is always in contact with the (vertical) edge of the dish (which prevents the cube from falling outside the dish itself). There is friction between the cube and the dish. The dish can rotate around...
  19. G

    Engineering Which Book Best Aligns with These Fluid Dynamics Topics?

    I'm looking for a book to really help hit home what my fluids class is teaching because I'd like to eventually learn the Navier Stokes Equation. Syllabus: 1. Introduction, definitions, fluid kinematics 2. Hydrostatics, including nanometers, Bourdon gauges and pressure transducers 3. Control...
  20. V

    A doubt from rigid body dynamics

    in rigid body dynamics is this relation between velocity of centre of mas and velocity of any particle in the rigid body correct? vcm = vp + rXω r is the position vector of the particle with respect to centre of mass relations are written in vector form and also tell me how to calculate...
  21. V

    A problem in rigid body dynamics

    Homework Statement A disc of mass M and radius r is kept on a horizontal,frictional plane and is connected to a horizontal spring at the centre.A particle of mass m strikes the topmost point of the disc,tangentially and sticks to it.Assume that the mass of the particle is m and it's velocity is...
  22. K

    Dynamics - Need help understanding Coriolis acceleration

    Homework Statement Homework Equations Coriolis Accel = 2*v*w Where w is the angular velocity and v is the linear velocity. The Attempt at a Solution I really just need help on understanding how the Coriolis acceleration in this problem is depicted. My dynamics book is extremely confusing...
  23. kev931210

    Stochastic dynamics and Angular velocity of a molecular motor

    Homework Statement Homework Equations Langevin equation (I included all the equations in the next section.[/B]The Attempt at a Solution I do not know how I can proceed from this point. I'm stuck since I have no information on the drag coefficient. Maybe my approach is wrong, and there may...
  24. A

    What is a very weak shock wave? (Gas Dynamics)

    I stumbled upon this concept when studying gas dynamics. What I get from my readings it must occur when Mach number is really close to 1. But I didn't understand how the property relations across a shock wave is affected by it.
  25. K

    Dynamics - Very simple Q; Just need clarification

    Homework Statement Homework Equations Skipping this, as I just have a simple question The Attempt at a Solution Here is the full solution, but I just have one simple question about a simple step. On the part for disk B, they establish the equation vD = vB - vD/B. In the proceeding step...
  26. V

    Understanding the Dynamics of Acceleration in the Wedge Problem

    In the adjoining figure if acceleration of M with respect to ground is a, then A) Acceleration of m with respect to M is a B) Acceleration of m with respect to ground is asin(α/2) C) Acceleration of m with respect to ground is a D) Acceleration of m with respect to ground is atan(α) The 2nd...
  27. jdawg

    What Are the Angular Velocity and Acceleration in This Mechanism?

    Homework Statement Block D of the mechanism is confined to move within the slot of member CB . Link AD is rotating at a constant rate of ωAD = 4 rad/s measured counterclockwise. Suppose that a = 350 mm , b = 200 mm. Find wCB and αCD Homework EquationsThe Attempt at a Solution [/B] I hope its...
  28. S

    Basic 1-d dynamics with a bit of calculus.

    Homework Statement A 500 kg boat moves with an initial speed of 20 m/s turns off it engine and slows down due to the drag force. If this force has magnitude F= 15.3v^2 find the boat speed after 12 seconds.Homework Equations ∑F = ma dv = adt The Attempt at a Solution taking the side opposite...
  29. jdawg

    Dynamics: Relative Motion Analysis

    Homework Statement [/B] If bar AB has an angular velocity of 6 rad/s, determine the velocity of the slider block C at the instant shown. 2. Homework Equations The Attempt at a Solution vB=vA+wABxrB/A vA=0 vB= -0.8485i+0.8485j So then C relative to B: vC=vB+wBCxrC/B -vCi=...
  30. I

    Dynamics and Kinematics Interview Question Examples

    So, my teacher is going to do almost like an interview to the class, asking our knowledge about Dynamics and Kinematics, and I was wondering if I can get questions to test my knowledge in Dynamics and Kinematics to get ready for it.
  31. I

    Dynamics Skier on a Slope Problem

    Homework Statement A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7 m/s. The coefficient of kinetic friction between skis and snow is 0.11. Determine how far the skier will slide before coming to rest. Answer...
  32. I

    What are the forces acting on a child pulling a wagon up an inclined hill?

    Homework Statement A child is pulling a wagon of mass 7.38 kg up a hill inclined at an angle of 14.3 degrees to the horizontal. The child applies a force parallel to the hill. The acceleration of the wagon is 6.45 cm/s^2 up the hill. Friction is negligible. Determine the magnitude of (a) the...
  33. S

    MHB Combination of field and particle methods for fluid dynamics

    hello, in numerical fluid dynamics there are field methods like finite-volume, finite-element, etc. and particle methods like Smoothed-Particle-Hydrodynamics – SPH and others. Both approaches have advantages and disadvantages depending on the application. Both, in principal completely different...
  34. Odious Suspect

    Feynman:"Laws of Dynamics" vs "Law of Dynamics"

    This is an observation, not a criticism. I noticed that in The Feynman Lectures on Physics Vol-I, Chapter 9 Newton's Laws of Dynamics in section 9.5 he speaks of "the law of dynamics" in the singular "That is where the law of dynamics comes in. The law of dynamics tells us what the...
  35. MacLaddy

    Engineering Alternative for Ogata System Dynamics?

    Because the section on frequency domain analysis (vibrations) is hurting my brain... Are there any alternatives to this book that may be a little less abstract? Thanks, Mac
  36. F

    Find Speed Changes for Spacecraft Orbit Transfer: Mplanet/MEarth = 0.75

    Question A spacecraft starts in elliptical orbit JK (red solid curve) around some planet and transfers to elliptical orbit MN (blue solid curve). To do so, it changes its speed at Kand inserts into the circular orbit KL (dashed green curve). At L, it changes speed again to insert into...
  37. Nader AbdlGhani

    Calculating Distance Covered by a Particle Using Displacement Vector

    Homework Statement The displacement vector of a particle of mass 50 gm. is given as a function in time (t) by the relation ##\vec S##=(5t-t2) ##\hat c## where ##\hat c## is a constant unit vector , s is measured in centimetre and t in second .Knowing that the particle started its motion at t=0...
  38. F

    Applied Nonlinear Dynamics & Chaos: Is It Possible to Jump In Mid-Book?

    Here is the table of contents of Nonlinear Dynamics and Chaos (by Strogatz) Overview Flows on the Line Bifurcations Flows on the Circle Linear Systems Phase Plane Limit Cycles Bifurcations Revisited Lorenz Equations One-Dimensional Maps Fractals Strange Attractors Last quarter, there was a...
  39. F

    Dynamics of material (momentum )

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hi, I am having difficulty solving the problem, please resolve it if possible. my work and the image for the problem is attached. Thanks The 10 kg block is at rest on the bottom of the incline (θ...
  40. C

    Dynamics of a Box attached to a pully

    Homework Statement Body A in Fig. 6-33 weighs 102 N, and body B weighs 32 N. The coefficients of friction between A and the incline are μs 0.56 and μk 0.25. Angle θ is 40. Let the positive direction of an x-axis be up the incline. In unit-vector notation, what is the acceleration of A if A is...
  41. datf

    Solving Fluid Dynamics Questions: Pump Similarity Laws and Efficiency Comparison

    Hi guys, please help me with these questions. I've been racking my brain for days but I'm not sure of the answers. 1) (Assume that pump similarity laws are valid and that the effects of Reynolds number (Re) are small.) A centrifugal pump operating at speed N is combined in series with an...
  42. S

    Relative Motion Analysis: Acceleration

    Mentor note: moved to homework forum later, therefore no template. When doing a rigid body relative motion (accel) problem using vector analysis, how do I know when it's appropriate to substitute sin/cos values vs when to use just the numbers given as the velocity?
  43. K

    Why Is Normal Force Not Equal to mg in Rotating Collar Problems?

    Homework Statement Homework Equations [/B] Radial and Transverse coordinates to relate acceleration Balancing forces The Attempt at a Solution I know that there is more to this problem, but my question is simple: Why don't we know what the normal force is? When I solved it myself I...
  44. Anakratis

    Bubble dynamics over a liquid surface

    Hey all, Interestingly enough, I was actually recently feeding some ducks at a nearby pond when I noticed a cool phenomenon that I couldn't explain myself, so I was hoping you guys could assist in that. When you have two air bubbles over a liquid surface, like water, they seem to accelerate...
  45. Asleky

    Dynamics: Incline Slope Derivation Simplification

    Homework Statement No official problem, just a study guide fill-in-the-blanks with an extended simplification blank. Basically, no values were given, and it is a standard block on a standard slope with a north-east applied force pushing down on the block (not parallel to horizontal or vertical...
  46. jdawg

    Dynamics: Spring Question Solution

    Homework Statement The collar has a mass of 30 kg and is supported on the rod having a coefficient of kinetic friction of 0.4. The attached spring has an unstretched length of 0.2 m and a stiffness of k =50 N/m. Determine the speed of the collar after the applied force F= 200N causes it to be...
  47. Jordan D

    Thermal Dynamics - Ring Heated Up

    Homework Statement This is more of a question that doesn't require formulas as much as common sense. The question goes,"If you have a ring that is heated up, would the hole in the middle get smaller or larger." Homework Equations N/A The Attempt at a Solution I know that when objects are...
  48. faradayscat

    Maximizing Fridge Stability: Determining the Optimal Height for Pushing Force

    Homework Statement say a fridge of width "w" and height "L" is being pushed on by a force F at an angle θ to the horizontal. This force is applied at a height of "h" above the ground. I want to know what the max value of h can be such that the fridge doesn't tip and the coefficient of...
  49. J

    Dynamics Problem about Velocity

    Homework Statement Hi guys, I was working on this problem and I want to know if it can be solved by using an indefinite integral, so here it goes: A car starts from rest and travels along a straight track such that it accelerates at 10 m/s^2 for 10 s, and then decelerates at 2 m/s^2 ...
  50. K

    Simple Dynamics Problem Requiring Explanation

    Homework Statement Boxes are placed on a slope at uniform intervals of time trelease and slide down the slope with uniform acceleration. Knowing that as a box B is released, the preceding box A has slid 6 meters down the slope and that 1 second later they are 10 meters apart, determine the...
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