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. Like Tony Stark

    Free body diagrams for boxes, inclined planes and springs

    FIRST PICTURE I have some doubts here because of the spring... I'll tell you what forces I've drawn. For ##A##, I drew the weight and the force applied by ##B## (the normal force) on the vertical axis; and the elastic force pointing to the right on the horizontal axis. For ##B##, I drew the...
  2. ValeForce46

    Cylinder with a horizontal tube (Fluid dynamics problem)

    I'll call ##v_2## the flow speed on the horizontal tube and ##v_1## the lowering speed of the column. Even if the lowering speed isn't negligible, the problem says "...when the plug has been removed", so can I consider the height unchanged? In order to find the force, I need the pressure when...
  3. Z0dCHiY8

    Why Is Space Travel More Complex Than It Seems?

    Most sources of pop culture & even engineering ones have failed to provide the key problems of space traveling. For example, dv ain't that hard as aerodynamics of Space. For 1st glance, it looks ridiculous == Space is Vacuum. Mostly, yes.. but Space has a lot of dust & gaseous clouds. Just one...
  4. ValeForce46

    Fluid dynamics problem -- Filling linked cylinders with water

    The first part of the problem I just used Stevin's law: $$p_{atm}=P+ρg(h_1-h_2)=> h_2=(P-p_{atm}+ρgh_1)/(ρg) =>h_2=0.94m$$ Is this right? I considered ##ρ=10^3 {kg/m^3}## About the second part... how can I be sure that ##h_1## remains unchanged? If it is unchanged, then can I use Bernoulli's...
  5. S

    Yo-yo on an accelerating conveyor belt

    First off, I was wondering if the acceleration of the conveyor belt can be considered a force. And I'm not exactly sure how to use Newton's second law if the object of the forces is itself on an accelerating surface. Also, I don't know whether it rolls with or without slipping. I thought I could...
  6. amare

    Practical application of engineering mechanics dynamics in civil engineering

    what is the practical application of engineering mechanics dynamics in civil engineering when civil engineers work on static analysis?
  7. Athi Sankar

    Dynamics of Machines - Forced Vibration

    Summary: I need a help to solve problem asked in university exam I am looking for the answer for the above question. I solved almost except the last one "Force exerted by the spring and dashpot on the motor". Can anyone help me to find out the answer for it
  8. A185

    Dynamics: A wedge, a mass, and two pulleys

    Problem Statement: In the arrangement shown in the figure, a block of mass m=2kg lies on the wedge of mass M=8kg.Find the initial acceleration of the wedge. Assume pulleys and thread massless and surfaces smooth. Relevant Equations: FBDs
  9. frostysh

    Exploring Chaos & Randomness in Deterministic Dynamics

    For myself is horrible to imagine that indeterministic randomness can appear in deterministic, absolutely known and visible dynamics. I have briefly look on the mathematics behind it and understand almost nothing... Well I have a very basic knowledge in mathematics. There is so-called "Rannou's...
  10. K

    Fluid dynamics and sound waves

    There are many fluid dynamics applications such as pipe flows, jet flows, boundary layers where we ignore any sound waves present in the system. I don't understand this though, because all sound waves are caused by pressure disturbances so why can we ignore these pressure disturbances when we...
  11. sandmanvgc

    Dynamics: Angular Acceleration Problem

    Both point A and B are moving in parallel in same direction, therefore rod is not rotating at this instance and angular acceleration is 0. Question states angular velocity is equal to zero. Plugging into Angular Acceleration"AB" = r*sqr(angular velocity"AB") = 0.26m* sqr(0) = 0 [Moderator's...
  12. R

    Failing in "Classical Dynamics": Seeking Advice for Pursuing a PhD

    Hello, PF members. This is my first post here. I got my undergrad result for final semester few days ago and to my surprise it showed that I have failed in 'classical dynamics'. This is not at all possible as I clearly remember it being easy and quite simple. What bothers me more is that I had...
  13. dRic2

    Reactor dynamics with a large reactivity insert

    I was wondering, if I want to understand qualitatively the response of a reactor to a large step insert of reactivity (e.g. more than 2/3 $) is it allowed to neglect the latent neutrons contribution to simplify the equations ?
  14. G

    Pendulum Hammer Impact Force Calculation

    Hi all, I'm a bit embarrassed but I'm extremely rusty with a lot of engineering principles. I've mainly been working in automation and controls within a manufacturing setting and have not done anything like this in ages. Anyways, I have a problem I need to solve and I need to determine the...
  15. aligator11

    Particle Dynamics Problem (kinematics)

    Summary: Mechanics problem related with Calculus (differential equations) Hi everyone, I would like some help in that task, if anyone would be willing to help :) Namely I have a problem from particle dynamics. "D:" means given info... so, D: m,g,h,b, miu. We're looking for v0 and S as given...
  16. A

    How to stop a steering wheel using an electric motor?

    Problem Statement: i have a steering wheel mounted on an electric motor, and i want to stop the driver from going beyond a certain angle. i can read the torque applied by the driver, and the steering wheel angular velocity as well. how can i stop the steering wheel, without sending it harshely...
  17. P

    What could be causing an ANSYS Explicit Dynamics error during solution process?

    I am trying to run explicit dynamics, but after AUTODYN PRE-SOLVER SETUP is complete the solution stops and the following message is displayed "A general failure occurred during the solution process." I have installed the same ansys version on another pc and everything works ok. RAM is the...
  18. O

    Dynamics Problem: Determine Velocity and Acceleration of Rigid body

    Hello, Wanted to know if this was the correct approach to solve this example. I uploaded the question along with an attempt. Thanks in advance.
  19. C

    Torque dynamics: Slotted screwdriver head

    See attached image I experienced yesterday that when the slotted screw driver head was exact fit to the slotted screw, it was easier to turn the screw into the hard wood. I'd like to understand the physics of it. Is the bottom (in the picture) easier to turn because there is even contact...
  20. Abhishek11235

    Solving this problem using the energy method

    I attempted the solution using force method. I got correct. However, I was stuck at the alternative way to solve problem using energy method. As shown in screenshot 2, he tells that the energy of system changes due to 2 ways: - The tension T - Leaking of mass As shown in screenshot 2 ,the...
  21. bardia sepehrnia

    Time needed for a Force F to accelerate the crate to 2m/s? (Dynamics)

    So above is the question. The picture below is my attempt at the solution: However the answer at the back of the book suggest that T=1.929s
  22. A

    Big Yo-Yo problem (Rotational Dynamics with Kinematics? Maybe?)

    What I attempted to do first was find alpha and turn that into translational acceleration. Taking mass of yoyo * radius of spool * gravity, (3kg)(0.8m)(9.81m/s^2) yielded 23.544 N*m, and dividing by I = 7.68 kg * m^2 yielded 3.065625 rad/s^2. Finally, multiplying by r = 0.8m gave me 2.4525...
  23. N

    Why does the displacement force act on AC - BC?

    Hi, I am having trouble understanding the intuition behind the problem I attached. Work is the product of the force and displacement in the direction of displacement, so since the crate is moving horizontally from A to B why isn't the displacement AB = 6m? Thanks in advance
  24. N

    How to show that P moves with a constant speed u

    For particle Q: The resultant force on particle Q would be zero since it is at rest. Thus$$ T - Mg = 0$$ which gives $$T = Mg$$ For particle P: This is where I am struggling. I can't seem to write out the polar equations of motion. I have to show that $$u^2 = (Mgb)/m$$ I know that $$\vec a =...
  25. WhiteWolf98

    Fluid Dynamics - Mass Conservation, State Equation for an Ideal Gas

    I understand that ##\dot m=\rho Q## and ##{\dot m}_{in}= {\dot m}_{out}## . So one can say that ##\rho Q_1 = \rho Q_2##. But I'm not sure if that equation is correct. I don't know if the density remains constant, or the volume flow rate. And then how I'm also supposed to tie a state equation in...
  26. Shridhar

    Rotational Dynamics, 1.68(SS.Krotov) and 1.264(Irodov)

    Homework Statement I have attatched both the problems. The figure is essentially the same. Homework Equations 1. Energy conservation 2.mgcosx - N = mv^2/r , where N is zero in limiting case. The Attempt at a Solution I solved the whole question and got the answer given in irodov(0.33...
  27. Sian R

    Curvilinear Dynamics and forces

    Homework Statement A wedge with face inclined at an angle θ to the horizontal is fixed to a rotating turntable. A block of mass m rests on the inclined plane and the coefficient of static friction between the block and the wedge is µ. The block is to remain at position R from the centre of...
  28. M

    Dynamics: Relative Acceleration

    Homework Statement The problem is in the image attached below 2. Homework Equations In the working below (although I think I have misunderstood a concept) The Attempt at a Solution My attempt is in the attached image. I tried to leave the numbers out until the end. I have not written...
  29. X

    Would acceleration under water affect the person?

    I've searched online over multiple sites and can find no answer to this. I know the basics on acceleration, mass and few others. To try and paint the right picture, take a person and put him in a hollow object--a tube shape--and accelerate them. They are subject to inertia. Now take that person...
  30. ?

    Rotating sphere which separates into hemispheres

    Hi all, The scenario I'm considering is a solid sphere (of uniform density) rotating with constant angular velocity when it abruptly splits into two hemispheres along a cut which contains the rotation axis. The hemispheres will begin to separate; if, for example, we consider the rotation to be...
  31. Abhishek11235

    Euler Equations for Dynamics of rigid body

    I have been studying the dynamics of free top from Morin's book. In his book when describing the dynamics,he writes down the equation of motion as shown in screenshot. However,I am not able to understand which term refers to which coordinate system. For eg: Here ##\omega## refers to angular...
  32. kelvin scott

    Calculate Linear Acceleration of 0.5kg Mass Suspended from Flywheel

    A mass of 0.5kg is suspended from a flywheel is released from rest and falls a distance of 0.5m in 1.5s ,calculate the linear acceleration of the mass Σ Torque = I x a Σ F = m* a Im I right with the formulas?
  33. Keith Mackie

    Uncovering the Origins of Dynamics: From Lucretius to Hobbs and Beyond

    You will get a very nice understanding of the origins of dynamics if you go back to the very beginnings: 1. Lucretius: De Rerum Natura - The Nature of Things published about 60 BC - about the time of Julius Caesar - Chaper 2, The Dance of the Atoms, an introduction to the eariest forms of...
  34. A

    Flight Path Angle and Velocity During Atmospheric Re-entry

    A space vehicle enters the sensible atmosphere of the Earth (300,000 ft) with a velocity of 25,000 ft/sec at a flight-path angle of -60 degrees. What is its velocity and flight-path angle at an altitude of 100 nautical miles during descent? (Assuming no drag or perturbations, two body orbital...
  35. T

    A ball (sphere) rotating along a moving incline

    Homework Statement We have a ball of mass ##m##and radius ##r##. it is placed on an incline (We don't know the angle of the incline, nor we do whether the angle is constant along the incline - maybe it is a curved incline) and then released. The COM of ball is ##h## meters above the incline at...
  36. Alex Petrosyan

    Relativistic Dynamics in Hamiltonian Formulation

    hi all! I’m trying to generalise the Caldeira-Leggett Hamiltonian (heat bath + particle) to the case of high velocities. Naturally, the multi-oscillator Hamiltonian needs to change and I have a gnawing suspicion that the multi-particle Hamiltonian is just the sum of single-particle hamiltonians...
  37. NickTheFill

    Exploring Dynamics of Dual-Length Springs

    Hi all, If two springs with the same stiffness rate but different lengths are connected together one inside the other so that at equilibrium one is in tension and the other is in compression how will the whole system behave if an external force is applied?
  38. S

    Principles similar to aero, hydro dynamics

    When you see a heavy airliner on landing approach, you'd be amaze how such heavy object can float in air. Not many know it's the air pressure differences that can cause it. There are still many who thought it was simply because the wings flap like birds. It's similar to aircraft carrier...
  39. L

    Relativistic Dynamics Problem - Reference Frames

    Homework Statement Two images are attached. The first image details the problem. The second image has an x',y' coordinate system depiction of the problem. Homework Equations The total energy of a particle is defined as E = mc^2, with m = γ*m_0. The Attempt at a Solution If the x', y'...
  40. T

    Atwood machine with variable mass

    Homework Statement We have an Atwood machine like the picture below. one side (left) is a bucket full of water which has a hole on the bottom and the water is flowing with rate ##dm/dt = \alpha = const##. The initial mass of bucket with the water is ##m_0##. On the other side (right) we have a...
  41. physics_cosmos

    Dynamics of a string coupled pendulum

    Homework Statement My problem/task is to explain in elementary terms the dynamics of a string coupled pendulum, the same as in this diagram: Is it simple to make a free body diagram for the pendulums? Is it possible to understand the motion as being caused by SHM oscillation of the top...
  42. P

    Is this kind of pressure chamber design possible?

    Hi! Given that the chamber is airtight and no air leakage occurs, is the design in the picture below possible? Can the pressure inside the chamber cause the button (black part at the top) to be "pushed"? https://imgur.com/a/wOSD30D Obviously the temperatures are over-exaggerated, but the...
  43. ikihi

    Fluid dynamics: pressure in pipes

    So I've been discussing this problem with my plumber dad. I uploaded the picture. I'm wondering if the pressure would change in the red pipe since the diameter decreases to 4 cm. Assume the 1st 10 cm pipe is full with water. Question: If the home pressure is 517 kPa going through first pipe...
  44. omega_minus

    Rotational dynamics of mono-domain magnetic nanoparticles

    Hi, I have a question about the rotation of a single-domain magnetic nanoparticle that is suspended in a ferrofluid immersed in an external field. Specifically, I am trying to work out the path that a normal vector on the surface of the sphere traces out in time. There are 2 ways the...
  45. L

    Other Asking for recommendation on Fluid Dynamics and CFD textbooks

    Dear All I am an undergraduate student studying in physics. I would probably get into research that needed fluid dynamics and CFD (computational fluid dynamics) skills. Previously I have not been taking a formal fluid dynamics course since there is none. I would like to pick up those skills by...
  46. Akash47

    Decreasing size of person's shadow as they walk toward a lamp

    Homework Statement If a man of height 6ft moves with 5ft/sec velocity towards a lamp hanging at 15ft height, then at what rate his shadow will decrease? Homework Equations Not sure but dynamic equations can help. The Attempt at a Solution I have no idea about how I can approach.So I want some...
  47. L

    Studying How to approach ME System Dynamics problems?

    In Summary: I have a test Friday in modeling mass-spring-pulley systems, and I'm struggling to tie everything together. We're using the textbook System Dynamics 3rd Edition by William Palm III, and while it does a great job describing the individual components of each system, it does a crappy...
  48. L

    Equation of Motion of a System of Springs (System Dynamics)

    I'm having trouble understanding the forces involved when defining the equation of motion for this particular problem. So... I've seen the answer for the eq. of motion worked two different ways. The first way involves combining the spring series into Keq = K1⋅K2/(K1+K2). The answer, plugging...
  49. L

    How can I calculate the force of a falling object?

    Today I was thinking how would I calculate the amount of force I would experience if I were to jump out of a second floor building in the event of a fire and if I had to jump how much force would be applied to me? I was able to find the height of the building by dropping an object from rest out...
  50. JTC

    Contributions to Dynamics - China

    Hello, To ensconce this question properly, we know that some of the major contributions to the discipline of rigid body and classical particle dynamics came from: Newton, Euler, Hamilton, Lagrange and so on... (no need to suggest other western names right now - I am aware of them). However I...
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