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. F

    Question on Rotational Dynamics of Yoyo

    Homework Statement Please see attached picture. Homework Equations Shown in picture The Attempt at a Solution It's a textbook example that has a solution. At the middle right hand side of the picture, they say "From Eq... Vcm = Rw" (Where 'cm' is centre of mass) I don't understand why this is...
  2. R

    Understanding frequency and dynamics

    Can someone please explain intuitively how the terms “frequency” and “dynamics” are related ? I understand the concept of each of these two individually, but I am having some difficulty visualizing what high-frequency dynamics mean. I understand the concept of how time and frequency domains...
  3. laramman2

    Applied What Are the Best Textbooks for Self-Studying Nonlinear Dynamics?

    What textbooks would you recommend for self studying Nonlinear Dynamics? I am a undergraduate junior who will be doing research on nonlinearity of spiking neurons. I have taken courses on ODE, vector calculus, probability, statistics, and linear algebra.
  4. anorlunda

    Are Modern Engineering Students Adequately Prepared for Motor Analysis?

    A recent thread started with this OP That OP and the answers that followed seem terribly overwrought as they struggled to answer using mostly verbage. IMO, the OP could be answered better and with less effort with a block diagram. The OP of that quesition asked what happens if you vary one...
  5. A

    Calculating Tension in a Hypothetical Moon-Earth System

    Homework Statement Suppose the moon were held in its orbit not by gravity but by a massless cable attached to the center of the earth. Find the tension in the cable. Homework Equations F=ma a=v^2/r v=2πr/T (since the pictures aren't working, I'm just going to post the url to the image)...
  6. AdityaDev

    Vessel of water under free fall

    When a Vessel of water is under free fall and there is a hole in the side of the vessel, why does no water come out of the vessel? (its given in my textbook that pressure exerted on sides of vessel is zero. But what does the horizontal force have to do with the vertically acting force due to...
  7. E

    Ferris wheel dynamics (swinging bucket)

    What mass is required to keep the seat of a ferris wheel from swinging no more than 30 degrees measured from the vertical axis? So let's say we have a big ferris wheel with radius R and its spinning at 10 RPM. At the end of the ferris wheel, is a hinge, and a hanging bucket (like the picture)...
  8. M

    Understanding use of accelerometers

    Homework Statement Imagine this: A rod is attached at one end to a rotating shaft. So, as the shaft rotates from 0 to 90 degrees back-and-forth (in the xy plane), so does the rod. My goal is to measure the instantaneous acceleration of the rod while its moving. I have a few 3-axis...
  9. K

    Population Dynamics: Logistic Model (Differential Equations)

    Homework Statement Population Dynamics: Logistic model. Suppose the environmental carrying capacity of the population is 100000 and the growth rate a t=0 is 5%. . If the population starts at 10000, how long does it take for the population to reach half the carrying capacity? dp/dt = A P...
  10. S

    Dynamics pythagorean confusion

    Homework Statement In position 1, the 0.25kg block is held against the spring, compressing it by 150mm. the block then is released, and the spring fires it up the cylindrical surface. Neglecting friction, find the contact force exerted on the block by the surface in position 2.[/B] 1/2kx^2 -...
  11. S

    Dynamics question: work and energy (spring problem)

    Homework Statement i just want everybody to check if my solution is correct.. because I am not confident with this one.. your help would be highly appreciated Question: The 0.31kg mass slides on a frictionless wire that lies in the vertical plane. The ideal spring attached to the mass has a...
  12. parabola

    Help with high school dynamics assignment?

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > I've searched for help before posting, found this thread that is asking for the same assignment by unfinished so I'll just copy and paste lol...
  13. cvex

    How to calculate velocities/forces from sphere collisions?

    Hi, Basically I have a point cloud that represents balls with different radii. They are all moving based on forces and sometimes they are intersecting with each other. Imagine the yellow ball is going in one direction while the blue balls goes in another direction. At one time they are...
  14. Feodalherren

    Computational fluid dynamics: steady 2D flow

    1. Homework Statement Homework Equations CFD The Attempt at a Solution I'm a bit confused by this question. So at first what I do for the problem on the left, I find the changes in the velocities in X and and Y on all four sides. I notice that the values on the diagram to the left are...
  15. A

    Direction of instantaneous axis in rigid body dynamics

    The general motion of a rigid body can be considered to be a combination of (i) a motion of its centre of mass about an axis, and (ii) its motion about an instantaneous axis passing through the centre of mass. These axes need not be stationary. Consider, for example, a thin uniform disc welded...
  16. A

    Difference between statics, dynamics, kinematics and kinetics

    Dear All, I am often get confused when four terms STATICS,DYNAMICS,KINEMATICS and KINETICS are used in physics Mechanics.can someone please differentiate between these four terms.i will be thankful.
  17. G

    Problems in explicit dynamics simulation in ANSYS Workbench

    I'm new with ansys if I can help it would be helpful. the problem is that two solids are shocked, but one of them is going through the other, have already implemented several things different tutorials but the answer is the same. the only question when I change the location fixed support the...
  18. G

    Is there a quantum mechanics theory for dynamics in QW planar VCSELs?

    Is there a theory of dynamics in VCSEL lasers? Especially polarization dynamics? So far I confronted mostly empirical derivations with a bunch of coefficients. I was wondering if there is a more general theory, probably based on quantum mechanics, concerning dynamics in VCSELs? If so, please...
  19. Feodalherren

    Fluid Dynamics: Conservation of momentum equation

    Homework Statement Homework Equations Conservation of linear momentum for fluids The Attempt at a Solution This seemingly simple problem has me confused. First of all, I want to set up the sum of the foces as: -Min + Mout -Fx = 0 So first of all, not only does my Fx term have the wrong...
  20. H

    Mass needed for static equilibrium compound pulley system

    Homework Statement For what m1 will the illustrated pulley system be in static equilibrium if m2 = 60 kg? Homework EquationsThe Attempt at a Solution im supposed to use the change in lengths but don't know how to do it
  21. marcus

    Smolin: Extending dualities to trialities (deepens dynamics)

    Looks like something special happening here: http://arxiv.org/abs/1503.01424 Extending dualities to trialities deepens the foundations of dynamics Lee Smolin (Submitted on 4 Mar 2015) Dualities are often supposed to be foundational, but they may come into conflict with background independence...
  22. JamesB93

    Dynamics assignment, power output of car

    I'm currently studying Mechanical Engineering at Level 3 in the UK and I'm beginning my integrated masters in September. I've missed a large chunk of my studies this year due to a broken collarbone I sustained earlier in the year. Instead of getting any special dispensation I'm trying to work my...
  23. A

    Fluid dynamics question (Poiseuille)

    Hi, I'm attempting to do a question involving blood flowing through a blood vessel and I'm incredibly stuck and would appreciate some help. The question is as follows: 'A simplified model of blood flow through the human body makes the approximation that the flow I is proportional to the pressure...
  24. X

    Inclined plane normal force varies by coordinate system?

    Suppose we have a block on an inclined plane. If we choose the x-y axis to be parallel and perpendicular to the inclined plane, then we have Fy = N - mgcos30 = 0 But if we choose our trivial x-y coordinate system, where y is parallel to the force of gravity, then we get: Fy = Ncos30 - mg =...
  25. X

    Why Do Different Methods Yield Different Accelerations in This Friction Problem?

    Homework Statement Homework Equations F=ma Ff = N u The Attempt at a Solution Pretty much, I did the same thing in the solution. For box A: N = mg Ffs = mg*uk = 9.81*20*.4=78.48N I note that Ffs > 60 N, so the boxes will move with the same acceleration Now there are two ways I can...
  26. X

    Conservation of momentum in a system, direction changes?

    We all know that momentum is conserved in a system. But I am confused of one thing. Suppose we have a system containing a wall with very large mass and a ball and use a classical x-y coordinate axis. If I swing the ball at an angle of 45 degrees from the horizontal, upwards to the huge wall...
  27. X

    What is the velocity of cart B after the boy lands on it?

    Homework Statement The 75kg boy leaps off the cart A with a horizontal velocity of v' = 3 m/s to the left measured relative to the cart. Determine the velocity of cart A just after the jump. If he then lands on cart B with the same velocity that he left cart A, determine the velocity of cart...
  28. X

    Momentum, why can we change the system?

    Here is our momentum equation for when two separate masses m1 and m2 collide with each other and couple together m1v1 + m2v2 = (m1+m2)v3 In the LHS of our equation, we have two systems. m1 and m2. But in the RHS of our equation, we use a totally different system. m3, the combination of m1...
  29. X

    Treating multiple objects as the same system

    Throughout my limited physics career (high school, first year university) I was introduced to concepts such as potential energy, kinetic energy, and work. Naturally, I was taught about potential energy using the whole gravity analogy. A brick at height h has more potential energy than a brick...
  30. N

    How can I simulate a rolling non-rigid tire with obstacles using ANSYS 14.5?

    Urgent help required! I need to simulate a rolling non-rigid tyre on a ground with obstacle(s). How should i proceed with ansys 14.5? Any help will be deeply appreciated.
  31. OmCheeto

    NASA NASA's Solar Dynamics Observatory, 5 year video

    I didn't know where to post this, but, this video makes my eyes water.
  32. Feodalherren

    ME Dynamics - Multiple ideal pulleys + an inclined plane

    Homework Statement Find the acceleration of both blocks Homework Equations Dynamics The Attempt at a Solution Everything in black is given in the problem. The red/blue is my work. First I want to relate the acceleration of block A to block B by finding the constraint equations: Lrope = 2L1...
  33. N

    Why does Newtonian dynamics break down at the speed of light

    I tried searching the web for this topic but got an answer like "formulae used in classical mechanics are approximations or simplifications of more accurate formulae such as the ones in quantum mechanics and special relativity". My question is that why do the laws of Sir Isaac Newton no longer...
  34. L

    What is faster the cannon ball or its shadow?

    I'm trying to finish my physics homework and one of the questions is somewhat philosophical. Problem: A cannon ball is shot at noon (12pm), what is faster? The cannon ball or its shadow? That's all the question is :p
  35. T

    Fluid dynamics - find velocity of a particle in a vector fie

    Homework Statement Determine the speed of a fluid particle at the origin and at a point (1,-2,0) for each of the following velocity fields when t = 2s. All distances are in meters and t is in seconds. V = (x+2)i + xtj - zk m/s Homework Equations V x dr = 0 dV/dt = u(dV/dx) + v(dV/dy) +...
  36. T

    Pressure and velocity calculation for microchannel. pls help

    Me and my friends have been trying (b) for soooo long! we have gone to PhD students and some fluid dynamic doctors for held and they cannot figure this out. 1. Homework Statement 2) This question concerns the design of a ‘micro-chemostat’ device. E. coli exhibiting chemotaxis can swim up to...
  37. Feeble Wonk

    Has There Been Further Progress in Shape Dynamics Theory?

    As a non-physicist, what little I have learned about Shape Dynamics theory is appealing to me in many ways. http://arxiv.org/abs/1105.0183 I offer this link as a starting point for the discussion, but I'm curious if there has been any further progress in the professional and/or academic ranks...
  38. T

    Finding acceleration given normal component [Dynamics]

    Homework Statement [/B] A belt moves over three pulleys at a constant speed v0 [ft/s]. Knowing that the normal component of the acceleration of the portion of the belt in contact with pulley B is aB,n=90 [ft/s2 ]. Determine: (a) speed of the belt, v0 [ft/s], and (b) normal component of the...
  39. F

    Dynamics Homework Help, velocity, acceleration of particle

    I need help with my dynamics homework. This is what I have so far, I hope you can read my writing (let me know if something is unclear). Can someone help me with how to approach this problem and where to go next? Thank you!
  40. P

    How Do Internal Combustion Engines Adjust to Changes in Speed and Torque Demand?

    hello I am interested to know in detail, how internal combustion engines work dynamically, ie. as the demand for speed and torque change what happens exactly? I know that when we want more speed/torque, we push the gas pedal, but what happens exactly between that moment and the increased rpm...
  41. N

    Roman Inverted Siphons and Fluid Dynamics

    Homework Statement "Inverted siphons were used by the Romans to cross some valleys. If the height difference between the top of the valley and the bottom is 10 meters, the pressure in the pipe at the bottom of the valley will be ____. Homework Equations Bernoulli's Equation P1+(pv^2)/2 + pgh1...
  42. T

    HNC Dynamics help please -- Hoist cable looped over a winding drum

    Hi guys I am looking for help with some formulas, its for hnc mech eng, the question is as follows a winding drum with moment of inertia 24 kg m2 and a winding radius of 0.6m is used to accelerate a loaded hoist with mass of 850kg at a rate of 0.8ms by means of a cable, frictional resistance can...
  43. U

    Pendulum - Stability and fixed points

    Homework Statement (a): Show the lagrangian derivative in phase space (b)i: Show how the phase space evolves over time and how they converge (b)ii: Find the fixed points and stability and sketch phase diagram (c)i: Find fixed points and stability (c)ii: Show stable limit cycles exist for T>ga...
  44. K

    How to calculate external force acting on a pendulum

    I am doing a physics project whose purpose involves describing the physics behind a toy. The toy I have selected is a "decision maker" which is composed of a pendulum which has a magnetically charged ball on it that swings side to side, while having a force exerted on it by magnets which change...
  45. Y

    How Do You Calculate Elevator Cable Tension for Maximum Acceleration?

    1. The problem statement, all variables and given/known data An elevator(4850kg) is to be designed so that the maximum acceleration is 0.068m/s2. What are the minumum and maximum forces the motor must exert on the supporting cable? 2. Homework Equations Force = mass(acceleration) Forcevertical...
  46. Y

    Dynamics: Newton's Second Law_Tension_1

    Homework Statement *Note: I'm really stuck in this part of Newton's 2nd Law so I may be asking a few more questions after this to practice for our upcoming examinations. A cable supporting a 2125kg elevator has a maximum strength of 21750N. What maximum upward acceleration can it give without...
  47. Y

    Calculating Acceleration and Force in a Racecar: A Newtonian Approach

    Homework Statement Here's the problem: A particular racecarcan cover a quartermile track (402m) in 6.40s starting from standstill. Assuming that the acceleration is constant, how many "g's"(all i know is that it means accleration due to gravity) does the driver experience? If the combined mass...
  48. H

    Do I understand this correctly?

    Homework Statement the theory behind Parallel axis theorem Homework Equations parallel axis theorem:Io=Ig+md² Radius of Gyration=Ig=m*K² The Attempt at a Solution ok folks If I understand this theory correctly the radius of gyration is the radius or distance from the axis of rotation to the...
  49. F

    Dynamics Problem -- box accelerated horizontally via a mass & pulley system

    Homework Statement A 1.0 kg box on a horizontal frictionless surface is accelerated by attaching a 1.5 kg mass as shown in the diagram. What is the magnitude of acceleration of the box?(Remember, both boxes accelerate.) Homework Equations F = ma The Attempt at a Solution I drew a free body...
  50. T

    Solve Mass-Spring Model: Find Shear Force

    Homework Statement A half-full water tank mounted on the top of a building is modeled as shown below. Find the shear force it can produce? m = 500 kg k = 1000 N/m model: https://app.box.com/s/qke2kbwag2mp9a23kkqq Homework Equations Transfer Matrix Method: Point & Field Matrices...
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