# What is Dynamic: Definition and 477 Discussions

Dynamic is an Italian independent record label located in Genoa. Founded in 1978, it specialises in classical music and opera, especially rarely performed works and has produced several world premiere recordings. The Dynamic catalogue contains over 400 titles, with about 25 new titles added each year and is distributed in 32 countries.

View More On Wikipedia.org
1. ### Why Isn't the Right Side Negative in a Vertical Spring-Mass System Equation?

I have a doubt with the last part. Why isn't the right side negative? Because when the block is released, it moves upwards. thanks image was obtained from here Thanks.
2. ### Acceleration of stacked blocks on an inclined plane

In order to calculate the acceleration, I sum the equations sum fx^B and sum fx^A. F_{r,B} - m_Ag sin(theta) - (m_A+m_B) g sin(theta) = - (m_A+m_B) a then a = -[F_{r,B} - (2 m_A+m_B) g sin(theta)]/(m_A+m_B) =-[muk (m_A+m_B) g cos(theta) - (2 m_A+m_B) g sin(theta)]/(m_A+m_B) but the...
3. ### I need sources to learn about dynamic systems

Hi! I have exam in couple of weeks , and now am looking for sources to learn about dynamic systems , chaotic systems and etc. My main goal is to learn characteristics of such systems , learn about special points in dynamic plane. For the most part we used to create dynamic system simulations...
4. ### Galactic Dynamic Homework （Problem 2.1 of B&T)

TL;DR Summary: Why the topic give the condition "limρr^5/2=0“？What is the usefulness of this condition？ Thanks!
5. ### Is the Instantaneous Circle Proven When Centripetal Force is Removed?

Can someone show that the instantaneous circle is indeed given by when the centripetal force is removed? This can be found at https://www.vedantu.com/iit-jee/circular-motion
6. ### B Find Geodesics in Dynamic Ellis Orbits Metric

Does anyone see a way I can find geodesics in the metric ##ds^2=-dt^2+dp^2+(5p^2+4t^2)d\phi^2## (ones with nonzero angular momentum)? I'm hoping it can be done analytically, but that may be wishful thinking. FYI, this is the metric listed at the bottom of the Wikipedia article about Ellis Wormholes.
7. ### How to calculate the speed of this umbrella extension arm?

TL;DR Summary: Have a university project where we are calculating the speed of the arm at the end. I need some help on where to start on the calculations. We have tried to determine instantaneous center of rotation for the device. We want to find the linear velocioty of point B. There is a...
8. ### Raspberry Pi 4 / Debian : Static IP on one SSID and Dynamic on another

My Raspberry Pi 4 has a GUI widget that is supposed to let us specify WLAN settings on a per-SSID basis, but it doesn't work. (All SSIDs end up with the same setting). Some articles on the net say that one can modify the dhcpd.conf file with an entry headed by the SSID name and then put in...
9. ### Engineering Dynamic physical model - automobile wheel suspension confusion

Been a long time I studied physics that had anything to do with mechanics, so I'm now in need of memorizing almost everything. So I am seeking for some guidance here. This is "system simulation/modeling/discrete event system simulation/etc" type of subject. The first thing that I didn't...
10. ### Number of collisions by a bullet

How to find the collision number if the moving bullet hits a few wooden blocks and every collision takes 10 percent of its speed. In which block will the bullet stay?
11. ### What is magnitude of dynamic force?

Summary:: In a mass-spring system they talk about 'magnitude of dynamic force', what is meant with that? Hi! In a mass-spring system I read about the term: "magnitude of dynamic force" (see sketch). What is meant with that? I the end this is used to determine the accuracy as I understand it...
12. ### Dynamic Systems: Question about Isoclines of Systems

Hi, I was doing some practice problems online for dynamical systems and came across the following question about isoclines. It left me with 2 questions that I hoping to get some insight to. Question: 1. What are isoclines? (I have tried doing an internet search, but the results don't help me)...
13. ### Dynamic Systems: Poincaré-Bendixson Theorem finite # of equilibria

Homework Statement:: Can someone explain the finite number of equilibria outcome of the Poincaré-Bendixson Theorem? Relevant Equations:: Poincaré-Bendixson Theorem [Mentor Note -- General question moved from the schoolwork forums to the technical math forums] Hi, I was reading notes in...
14. ### Car that undergoes non-uniform circular motion

In the solution manual, it says that: the resultant of friction force is ##<= kmg##, hence $$m\sqrt{\omega_t^2 + (\frac {v^2} {R})^2} <= kmg$$ and from this equation, we will get $$v^2 <= R \sqrt{(kg)^2 -\omega_t^2}$$ which will make ##v_{max}^2= R \sqrt{(kg)^2 -\omega_t^2}## Finally, they...
15. ### MHB Static or dynamic integrity constraints

Hey! 😊 Classify the following statements according to static or dynamic integrity constraints, based on the database that is to be created in the thread https://mathhelpboards.com/threads/creating-tables-integrity-constraints.29157/. 1. A customer's discount may not exceed 50 percent. 2. The...
16. ### Optimization Problem - Dynamic Programming

Summary:: Hi, this is an exercise from an algorithm course. I have been trying for hours but I have no successful ideas on how to solve it. I can only understand that DP is the correct approach, since Greedy method does not work. Suppose you have *n* friends that wants to give you an amount of...
17. ### I Classical Mechanics - Motion of a particle

Show that a point with acceleration given by: a=c*((dr/dt)×r)/|r|3 where c is a constant, moves on the surface of a cone. This is jut an example to illustrate my doubt. I don't know how to obtain the tracjectory given only the acceleration in this format. I realized that if i can show that...
18. ### The Force components acting on an object

Another user suggested adding the forces in the x and y direction then dividing by 1.4. Doing this for A) gave me 4.285 which was wrong any suggestions?
19. ### A 2.0x10^4 kg rocket has a rocket motor that generates….

I tried A with the solution of 9.73 and 8.69 both wrong.
20. ### Object at rest hanging from two ropes

Here is where I am at : 1- F(C2/P) > F(C1/P) must be true I believe this is false, considering the angle separating C1 from the 'ceiling' is bigger 2- F(C2) > 10 N may be true I believe this is true because F(C2) could be broken down into vector components which may go above 10 N 3- Vector sum...
21. ### B Dynamic pressure in pressure units

We all know that a flowing fluid acquires dynamic pressure as a result of this velocity. But the pressure has been known to be the kinetic energy of unit volume of flow i.e. 0.5 times density multiplied by the square of the velocity. I just want to know how to convert that into units that are...
22. ### I Configuring Laws of Motion: Static/Dynamic

$$\Box A_\alpha +\mu^2 A_\alpha = 2\beta A_\mu \partial_\alpha A^\mu + \frac {4\pi}{c} J_\alpha$$ where ##A=(\Phi, \vec A)## and ##J=(\rho, \vec J)## using a static configuration first where ##α=0## and then a dynamic one where ##α=i## knowing that ##E= - \nabla^2 \Phi - \frac {\partial...
23. ### The 835kph Sailplane and Dynamic Soaring

I recommend this video. I'm very impressed by the engineering. 835kph, transonic effects, and 120G turns in a RC hobby aircraft; wow! From the video, I learned about aerodynamics, wind patterns around hills, the idea of dynamic soaring, airfoil design, controls coordination, ballast...
24. ### Annihilation: calculation of photon energies

I set up this problem this way: ##p_a^{\mu}=(E, \sqrt{E^2-m^2}, 0, 0)## ##p_b^{\mu}=(m, 0, 0, 0)## ##p_c^{\mu}=(2E_\gamma, 2E_\gamma, 0, 0)## I have chosen to consider the two photons as a single particle of energy equal to ##2E_\gamma##. At this point I applied conservation of the...
25. ### Conservation of Momentum in Dynamic Engineering Systems

Hi there could someone please help me with this question we have not been taught the content of this question what so ever so help would be very much appreciated. As you will be able to tell by the question it is not very difficult however I am not excellent at engineering or physics and...
26. ### Mathematica Tracking dynamic markers across plots (Mathematica)

Let's say we have a rectangular plot of two curves X(t) and Y(t); and next to it we have a parametric plot of (X(t) , Y(t)). Now we want to add a slider that can control markers on both plots, so that the slider ( = ts) moves two markers X(ts) and Y(ts) across the rectangular plot and at the...
27. ### Circuit theory - Resistor function for dynamic non linear circuits

Hi, I'm reading the following paper (L. Chua) about the state-of-art of dynamic non linear circuit analysis -- Chua_Dynamic_Circuits I've a doubt about Theorem 2 on section 3.2 On the Existence of the Resistor Function that establishes sufficient conditions for the existence of network...
28. ### Mathematica Show dynamic value as a number

In the example below, x is static while x1 is a dynamic copy of x. Also, y and z are similar expressions containing x and x1 respectively. If we evaluate expressions containing x and x1, they display in numeric and mathematical formats, respectively (y and z below). How can I display z as a...
29. ### Design of welds under dynamic (shock) loads

Hi, in the books about the design of welded connection, we can find detailed description of calculations for static and fatigue loads. But what about the other type of dynamic behavior - shock ? As an example consider welded parts of the tow hitch used to free vehicles stuck in mud. Of course...
30. ### B Relativistic Photon Mass: Can It Exist?

Photons have 0 rest mass. But could I talk about relativistic, or dynamic photon mass, that would be the solution of hf = mc^2 ? The relativistic mass would be m = m0/sqrt(1-v^2/c^2), where m0 is the rest mass, so 0, and v = c, so the denominator is also 0. The previous equations would give 0/0...
31. ### MHB Dynamic programming: which recurrence relation do we use?

Hey! :unsure: At the cash register of a store we want to give change of worth $V$ cents of euro. Create and analyze a greedy algorithm that gives the change using the minimum number of coins. Assume that the available coins are the euro subdivisions, i.e. $\{1, 2, 5, 10, 20, 50\}$ and that we...
32. ### Code / Software for Dynamic Balancing (Free / Open Source)

I am thinking of doing a DIY project in which one sub-task would be to dynamically balance a small assembly that will be spun up by, for example, a small motor taken from a DVD drive. As a test case, here is a setup where we would like to adjust screws S1 to S6 such that the cylinder is...
33. ### Write the equations of a mass and spring in different accelerated systems

Hi I know that the equation of a simple harmonic oscillator is ##\ddot x + \omega^2 x=0##. The thing is that I don't know how to get to that equation in the situations given. In the first situation, I know that ##x) k(x-x_0)=m(\ddot x -x \dot \theta ^2)## ##y) N=m(2 \dot x \dot \theta)## So...
34. ### Dynamic Equilibrium -- Acceleration of a rock thrown from a bridge

I know the acceleration of the rock is equal to g, but why. If we neglect air resistance, what is actually making the rock fall? Wouldn't it be that g overcomes the acceleration of the y plane at some point so the rock starts coming down or in this case accelerate more by throwing below 0 degrees?
35. ### I How can I accurately locate the front axis of an arrow for optimal flight?

I have studied arrows and arrow flight the best I can for a number of years owning an archery shop A number of years ago I began testing arrows in the shop which we refer to as a static test We look at straightness, deflection matching and weight matching We also test to find the stiffest...
36. ### The average rate of energy loss resulting from internal friction

Summary:: Having the following dates:
37. ### Dynamics homework -- Motion of a stick attached to a rolling disk

Hi everyone, I need help for this homework. I'm a mechatronics engineering student and i want to solve this question but no matter how hard I try, I can't solve the question. Sorry for my bad english...The disk connected to the AB stick with a length of 2 meters is rolled as shown in the figure...
38. ### I Evaluating Accuracy of Dynamic Model for Spreading Disease

I'm trying to dynamically model the scenario of a disease spreading across the population, modelling the number of cases, and I would love to hear your feedback. It's kinda different from the S-I-R model, and its also a crude model. First, we consider two numbers, NT and NA. NT is the total...
39. ### I Static and dynamic excited states

Hello! I am reading about excited levels in nuclei (I am mainly following Wong's nuclear physics book) and I am a bit confused about the nature of the excited states. In the one particle picture (mainly shell model) the excitation appears as static i.e. one nucleon moves from a certain orbital...
40. ### Dynamic Equations of the ADM Formalism

The main error in my earlier work was forgetting that to obtain ##\delta X## you have to find not only ##\frac {\partial X}{\partial g_{ij}}##, but also ##\big(-\frac {\partial X}{\partial g_{ij,k}}\big)_{,k}## and ##\big(\frac {\partial X}{\partial g_{ij,kl}}\big)_{,kl}##. I also missed a...
41. ### Dynamic Viscosity in Reynolds Number

I am trying to run a calculation to work out the overall heat transfer coefficient of an arbitrary ten plate exchanger where the fluid is not determined using Re=puD/mu where mu is dynamic viscosity. When mu is such a strong function of temperature how should I determine which valye to use, say...
42. ### An object with mass m moving on x'x and Ep(x) = (1/2)*k*(x^2 - 4)^2

Hi ! This is my try: Is that correct ? Thanks

45. ### Applied Master Slave schemes in dynamic systems

Does anyone know a good book on master-slave schemes in dynamic systems? I'm on a dynamics book covering oscillators and it kind of glances over the topic and expects me to know it. I've done previous basic dynamics books and haven't seen it in them and checking on the internet I have found very...
46. ### Find the force needed for a body on an inclined plane to be static?

Here, I have two doubts 1) if the surfaces are frictionless, then there's no force being applied on the ##x' axis## of ##m_1## except from the weight, so it should be sliding, shouldn't it? So, there's no force that I could apply to ##m_2## to keep ##m_1## in equilibrium since any force that I...
47. ### RLC Circuits: Exploring Dynamic Systems

Hi ! I'm trying to understand why does we say that RLC circuit is a dynamic system. An example of a dynamic system that i know is a pendulum. The swinging of a pendulum depends on the applied force but also on the past force. What about the output of RLC circuit ? What is the relation between...
48. ### A Does anyone know asymmetric dynamic global solutions to Einstein eqs?

https://link.springer.com/article/10.12942/lrr-2005-6 https://en.wikipedia.org/wiki/Exact_solutions_in_general_relativity http://www.numdam.org/article/SEDP_1989-1990____A15_0.pdf A moderator removed this off-topic discussion from another thread. Does anyone on the Physics Forums have...
49. ### Man on ladder: jump off instantly vs last moment?

So there are two cases: a). free fall (straight forward for me) b). ladder rotating and jumping off in last moment (I am interested in trying to understand this case) I believe I should take into account momentum at the time the man hits the ground in both cases? The smaller, the better. Or...
50. ### What is Static, Dynamic, Transient, and Persistent Local Resource in the discussion of Object Server and Middleware?

What I understand is, I have written something like this myself. What is a Static Proxy and a Dynamic Proxy then? Also, What is a Transient Proxy and a Persistent Proxy?