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. ramzerimar

    Dynamics problem: Crankshaft angular speed?

    Homework Statement Homework Equations Kinematic theorems: The Attempt at a Solution Ok, I'm trying to use another angle, phi, and find some relation betwen phi and theta so I can derive the equation for the angular velocity of rod B with respect to S, but I'm stuck at that point. How...
  2. E

    Determining the sign of control derivatives

    I'm having quite a deal of trouble trying to figure this out. Say, for example, you wanted to have a statically stable aircraft. How do you determine what the signs (positive or negative) of the control derivates need to be for this condition to be satisfied ( CXα, CZα, Cmα, Cmq, CZδe, etc) ?
  3. qnach

    Optical counterpart of duckbill check valve in fluid dynamics

    In fluid dynamics there is a duckbill check valve to prevent the reverse flow. In EM wave an antenna emmits/receive at the same efficiency. Is there anyway one can make a check valve for antenna so that it emmits more than received or vice versa...or perhaps emitts without even receive?
  4. synMehdi

    Automotive Solving Traction & Friction Issues with Car Simulation

    Hi, I'm simulating the behavior of a car and I have some troubles with the tires. Specially with slip when the car is accelerating. I've seen many documents over the internet and I understood 2 main things: Wheel slip is necessary to accelerate & the coefficient of friction depends on the slip...
  5. J

    Dynamics how to calculate maximum height on incline

    Homework Statement A 5.0kg block initally traveling at 11m/s moves up a 30degrees incline. A frictional force of 9.4N acts on the block as it moves up the incline. What maximum vertical height, h, will the block reach? m = 5.0kg, vi = 11m/s, vf = 0m/s, Fr = 9.4N, Homework Equations...
  6. D

    Revolving Motion: Speed & Acceleration

    Homework Statement Homework Equations The equation in the picture. The Attempt at a Solution I know I have to use the equation for r but I do not understand how to take of the 40 and 30 rev/min info.
  7. phinds

    Fluid dynamics of a cocktail shaker

    My son today asked me for an analysis of a situation, which was described to him as being purely anecdotal but apparently a fairly widespread belief among bartenders, so possibly correct. The description is that if you take the two metal halves of a cocktail shaker, with a normal compliment of...
  8. S

    Vector Field Dynamics: Apologies & Solutions

    Currently working through some exercises introducing myself to quantum field theory, however I'm completely lost with this problem. Let $$L$$ be a Lagrangian for for a real vector field $$A_\mu$$ with field strength $$F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu$$ gauge parameter...
  9. deusy

    Acceleration of the end of a hinged rod in a pulley system

    Homework Statement As shown in image. 2. Homework Equations Moment of inertia of pulley = 1/2*M*R^2 Moment of inertia of rod (about end) = 1/3*M*L^2 Acceleration of end of rod in theta direction = L*α Acceleration of end of rod in radial direction = L*ω^2 The Attempt at a Solution...
  10. C

    Applicability of potential flow theory (fluid dynamics)

    To start this question off, I'll just state what I do understand about potential flow theory 1.) I understand that the navier stokes equations are really difficult to solve analytically except in degenerate cases where the assumptions about the flow cancel out the non-linear terms. 2.) I...
  11. R

    Fluid dynamics: half submerged straw opening

    Homework Statement This is not a set question but a problem statement for an investigation. I am trying to understand the physics behind drinking through a straw, but not when the straw is fully submerged in the drink but at the end of the drink when the liquid and air both pass up the straw...
  12. dexterdev

    A Can a molecular dynamics simulation enter a limit cycle?

    In my rough understanding Molecular Dynamics using Classical Newtonian mechanics is a 6N dimensional non linear system. 6N dimension because you have 3 position vectors and 3 momentum vectors for each N particles. Nonlinearity because of the terms in force fields. In principle this system can...
  13. R

    Dynamics 1: Motion Along a Line

    << Mentor Note -- poster has been reminded to fill out the Attempt at the Solution part of the Template in future HH threads >> 1. Homework Statement An object of mass m is at rest at the top of a smooth slope of height h and length L. The coefficient of kinetic friction between the object and...
  14. BrainMan

    Dynamics in two dimensions problem

    Homework Statement Homework Equations xf = x0 + v0cos(θ)t + (1/2)axt2 yf = y0 + v0sinθt - (1/2)gt2 F = ma The Attempt at a Solution [/B] I first tried to find the acceleration in the x direction so I could solve for the force xf = x0 + v0cos(θ)t + (1/2)axt2 In order to find the time I used...
  15. T

    Derivation of Applied Force in a Grade 12 Force Question

    Homework Statement When an applied force elevated at angle θ is used to drag mass m along a surface with μ as the coefficient of friction, the mass accelerates horizontally with some value, a. Derive the cleanest and most simplified formula for the applied force, Fapplied, that will give the...
  16. C

    B String constant of a folded and a cut up rubber

    Imagine that we wanted to build a slingshot, using one piece of rubber attached to two hooks - each on a side. We use a rubber, whose spring constant is k. My questions are: 1. If we began to string that slingshot and the rubber would begin to fold, what would happen with the string...
  17. L

    Variational calculus or fluid dynamics for fluid rotating in a cup

    my first post having just joined! Problem statement - what curve describes the surface of a rotating liquid? Stirring my cup of coffee years ago sparked this thought. Question - is the way to solve this problem to use variational calculus, or fluid dynamics? I have always thought the former but...
  18. C

    Aquarium on a train during braking

    Homework Statement On a train, there is a passenger who has an aquarium, filled with water. The aquarium's size: 40cm x 25cm x 25cm, and is filled with water up to the height of 20cm (5 cm remaining) What is the maximal deceleration of the train, such as the entire volume of water will remain...
  19. RandomDude123

    Fluid Dynamics - Calculating Coefficient of Drag

    How would one calculate the drag on a projectile (in this case a 1cm3 cube) that was launched at 0°. The vertical drop, initial velocity, distance, and time (taken to travel distance) where measured. I want to say that I could compare these experimental drop (bellow hight that projectile was...
  20. W

    Can someone explain this derivation?

    Homework Statement I've been looking at examples of motion derivations for my class, and it's honestly just very confusing. I heard Dynamics should prep you for this but I must have had a very poor course because we never had to understand geometry and physics to this degree... Homework...
  21. Mr Davis 97

    Banked Turn: Navigating Car Dynamics on Curves

    Homework Statement A car enters a turn whose radius is ##R##. The road is banked at angle ##\theta##, and the coefficient of friction between the wheels and the road is ##\mu_s##. Find the minimum and maximum speeds of the car to stay on the road without skidding sideways Homework Equations...
  22. W

    Identifying the Potential Energy of a Spring Pulley System

    Homework Statement Homework Equations U = 1/2 kx2 The Attempt at a Solution So, I took dynamics off campus and needless to say, we didn't really do very much deriving so that aspect of physics really bogs me down and I'm trying to learn it now in another class. So if anyone wants to also...
  23. W

    Is the derivative in my textbook correct here?

    Homework Statement Homework Equations d/dx The Attempt at a Solution d/dx (T) = d/dx(1/2mx'2) = mx'' d/dx(U) = d/dx(1/2kx2) = kx' ≠ kx It's probably me who made an error because I know that that equation (2.3) is the one I should be getting, but I don't understand how they did it because...
  24. ramzerimar

    Dynamics problem: determine maximum angle for equilibrium

    Homework Statement A uniform bar with length c can slide a cylindrical surface with a radius of r. Determine the maximum angle theta that guarantees the equilibrium of the bar if the friction coefficient at the points of contact is u. Homework Equations Friction force = u*N (where N is the...
  25. Alexanddros81

    I don't understand a sample problem in Dynamics Beer

    Hi! I am new to this forum and i have problem understanding sample problem 13.5 from Vector Mechanics for Engineers 10th edition Statics and dynamics. (Beer) In particular I don't understant how in part b assigns the value aC=-1/2aD If anyone can help thanks
  26. C

    Calculating Acceleration of M1,M2 System w/ Friction

    Homework Statement A 500 g block lies on a horizontal tabletop. The coefficient of kinetic friction between the block and the surface is 0.25. The block is connected by a massless string to the second block with a mass of 300 g. The string passes over a light frictionless pulley. The system is...
  27. donaldparida

    B Can force be applied in vacuum?

    Is the capability to apply force dependent on the medium.Suppose two human beings are placed in vacuum.Now, can they apply forces on each other? Also, can force fields such as gravitational and electrical fields exist in vacuum and if so then why?
  28. C

    Preventing Bruises: The Benefits of Using Ice and Medication

    If you hit your feet or arms on hard object like corner of furniture.. you know it would form bruishes that turn bluish color days later.. but is there any advantage if you can avoid its formation by using ice or any med that can avoid the formation of the bluish colors later?
  29. Z

    Fluid Dynamics question -- compressibily of brake fluids "oil"

    As part of a racing community, there is a discussion going on that talks about compressibility of brake fluid. the Street car versions have a value of 6.5E-05 and the racing stuff is 4.5E-05 both at a pressure of near 5000psi. there is talk about the difference of the racing fluids which...
  30. N

    Dynamics -- Newton's 2nd law with acceleration

    Homework Statement A sleigh with a mass of 150 kg from rest is horizontally towed to the left . This is done using a rope that makes an angle of 30 ° with the horizontale. The tensile force is 200 N. (Neglect friction forces.) a. What is the horizontal component of the force? b. What...
  31. N

    How Do You Calculate Skier's Mass and Acceleration with Newton's Second Law?

    Homework Statement A skier glides down a slope, and has at the bottom of the slope, at the beginning of a horizontal piece, a velocity of 30 m / s. He begins to brake and after 4 seconds later has a speed of 10 m / s. The friction between the skis and the snow is 400 N during braking. a. What...
  32. S

    A Planar orbit of planets around sun

    Imagine thee planets interacting through gravity, mathematically how should they come and rotate in a same plane, like planets and sun?
  33. L

    In dynamics, do we assume springs always resist motion?

    I'm making a vibration rig that represents a classic 2 mass, 3 spring system (See attached Image). (To clarify the image - there will be no forcing frequency. m=m1=m2 and k=k1=k2=k3) I'm using extension springs in the vibration rig. I plan to displace them in extension at an equilibrium point...
  34. N

    How High is the Water in the Bottle Based on Fluid Dynamics?

    Homework Statement A water bottle has a tap tube at the bottom. The diameter of the valve opening is 1 cm. If you turn on the tap, the water drains out with a velocity of 1.4 m / s. If the air pressure in the bottle is equal to the atmospheric pressure outside it, how high the water than in the...
  35. N

    Fluid dynamics continuity equation

    Homework Statement Through a (cylindrical) heating tube, warm air has to flow with a velocity of 3m/s in order to heat a rectangular spacewhich is 12 m long, 10 m wide and 2.5 m high. How large the radius of the tube should be if the air in the room get refreshed every 15 minutes ? Assume that...
  36. M

    I N-body codes for planetary system dynamics

    A while back I did research in planetary system dynamics that involved the code package Mercury. Unfortunately, I found that Mercury would occasionally crash for no reason or give nonsensical results. This happened for a small subset of initial conditions and while I spent some time debugging...
  37. Clara Chung

    Rotation dynamics pulley concept confusion

    Homework Statement A light string is passed over a pulley and two masses m1 and m2 are suspended from the two free ends. The pulley is a uniform circular disc of mass M. Find the linear acceleration of the two masses. Friction may be neglected. Homework Equations I through center of the disc =...
  38. P

    Kinetic friction in an N,T- system only works in tangential?

    Homework Statement Homework Equations F=m*a ΣF(n-direction)= m*a(n)= m*(v^2/ρ) ∑F(t-direction)= m*a(t)\ Ffriction= Fn*coefficient(of friction) The Attempt at a Solution So I tried solving this question and apperently it is way easier than I thought. So I thought the kinetic friction has a...
  39. Clara Chung

    Rotational Dynamics Homework: Find Initial Angular Mom & Ang Vel When Bar Vert

    Homework Statement A uniform bar AB of length L is freely hinged at one end A and released from a horizontal position. a) Find the initial angular momentum. Ans: 3g/2L b)Find the angular velocity when the bar is vertical. Ans: (3g/L)^(1/2) Homework Equations momentum of inertial of a rod...
  40. dreens

    I Variational Equations, Chaos Indicators

    I work with an electromagnetic molecule trap, and I'd like to determine which orbits are chaotic. To this end, I intend to study the evolution of a perturbation on a trajectory with time. I'd like to compute something called the fast lyapunov indicator for various trajectories y(t), where I...
  41. P

    Simple dynamics question, answer seems incorrect....

    Homework Statement Homework Equations f=m*a V= Vg*cos θ The Attempt at a Solution Is this solution correct. I did everything the same, but I did not use the 15 ft/s. Since An= (v^2/ρ) with V being the velocity in the t direction. The 15 ft/s according to me is only the component of V that...
  42. R

    Using Kepler's 3rd Law to find Period of Venus

    Homework Statement Deduce, from the equations employed in Q4 and Q5, the exponent n in the equation: T = k rn where k is a constant and T is the period of a satellite which orbits at a radius r from a massive object in space. Hence, how long is the “year” on Venus if its distance from the Sun...
  43. P

    This solution does not make sense to me (dynamics)

    Homework Statement Homework Equations F=m*a The Attempt at a Solution Don't worry it not a homework question of mine. I was just trying to solve some questions (on my own) that I know I have difficulty with to get better at it. Especially with springs I can get confused, so I thought I...
  44. Clara Chung

    Calculating Normal Force on a Wedge with Friction: Basic Dynamics"

    Homework Statement A block of mass 5 kg rests on a wedge placed on a table. The mass of the wedge is 10 kg. The wedge has an incline of angle θ = 30 degrees. a) Find the normal reaction of the table acting on the wedge. ANS : 150N b) Repeat (a) if the block slides down the wedge without...
  45. Elien

    Fluid Dynamics in Pipe Lines Problem

    Hello! Please help me understand whether I'm going to the right direction with the solution or partially wrong or completely wrong. I have a basic Fluid Mechanics course at the uni, the following problem is from a past exam my teacher gave us to practice before the exam, so there're no answers...
  46. Eduardo1234

    Automotive Vehicle dynamics -- Accelerating FBD

    Im starting to learn about vehicle dynamics by watching video lectures here , and also reading the books by Gillepsie and Jazar. I´ve got a fundamental question about the FBD of the vehicle. According to Gillepsie :http://imgur.com/a/lGXxw http://imgur.com/a/lGXxw The vehicle is...
  47. P

    Dynamics; I don't get, nor see the wrong assumption.

    Homework Statement The 2-kg collar C is free to slide along the smooth shaft AB. Determine the acceleration of collar C if (a) the shaft is fixed from moving. (b) Collar A, which is fixed to shaft AB, moves downward at constant velocity along the vertical rod, and (c) collar A is subjected to a...
  48. Sqrt

    What is the net force on Box H when pushing on Box G with a horizontal force?

    Homework Statement Two cardboard boxes full of books are in contact with each other on a friction less table.Box H has twice the mass of Box G. If you push on box G with a horizontal force F, then box H will experience a net force of? 2. The attempt at a solution Let book G's mass be = m...
  49. S

    MHB Combined Buoyancy and Dynamics of Moving Mechanical Systems

    Hi All, So glad to have come across this amazing site and resource. I am a mature student completing an engineering degree with the Open University and I am after some guidance and help with creating a way to plot forces from a moving mechanical system. The images on the attached drawing are...
  50. Cleo James

    Minimum Vo for a hoop to get to the top

    Homework Statement part(b) and (c) Homework Equations Conservation of momentum Conservation of angular momentum Conservation of mechanical energy The Attempt at a Solution So first I thought that I could do it by just using the conservation of mechanical energy, but then I realized that since...
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