Dynamic Definition and 478 Threads

I have a Mathematics C assignment, with one question being about static and dynamic friction. But I think it fits this forum. Anyway, we need to conduct experiments to show if there is a difference between static and dynamic friction or not with three different surfaces. The weight of the...

The diaphragm in a dynamic microphone moves a wire coil in the presence of a magnet to induce a current related to the movement. Other types of microphones, like electret and condenser microphones have self noise - noise not attributable to the amplifier. I wonder if all of the "self noise"...

Homework Statement A glass tube is bent into a rectangular "U". Find expressions for the difference in the height hbetween the tops of the liquid columns when (a) the tube has linear acceleration a in the direction of the x-axis, (b) when the tube has uniform angular velocity ω about the...

Hi; I'm a new user of molecular dynamic code LAMMPS and I have a problem when I want first to compute samples problems.I beg erverybody who have already work with lammps to help me. When I want to compute the first examples called COLLOID; an error occurs like: "invalid pair_style".I would like...

Homework Statement The central moments of inertia of the gears A and B as shown are 10 kg.m2 and 20 kg.m2, respectively. If the mass of the block C is mC = 50 kg and the system is released from rest, determine alpha A of the gear A fig is attachedHomework Equations The Attempt at a Solution...

If the ball were rolling uphill, the force of friction would still be directed uphill as in FJg. 1O.19b. Can you see why'? http://img252.imageshack.us/img252/4516/rollingm.jpg I always assume the friction is always in opposite direction of the motion.

Dear all, I have written a code for dynamic analysis of a mechanical structure. My primary purpose is to find natural frequencies of the structure. When I test my code for a cantilever bar whose natural frequencies are known analytically, I found a big difference between the the first...

Can static pressure be induced to becoming dynamic pressure through the use of "right-angle forces" with respect to particle velocities? I imagine that one could accomplish this with an ionized gas and a magnetic field. This would reduce the amount of work that is need to accelerate the gas...

Hi all, I need to do a dynamic structural analysis using finite element method and I have a question about the mass matrix. Question: I have the force per nodes and I need to calculate the displacement of each node at a given time. For this purpose, it seems that I need to distribute the...

I am designing a survey to gather data on consumer preferences for notebooks (school club charity project). The survey will contain only 10 questions about what notebook designs they prefer. Thus, I only want them to see notebooks they are likely to want. I am not sure how to set up the...

Homework Statement Two teams A and B play at most 2n-1 games. For any match there is a constant probability p that A wins and a constant probability q=1-p that B wins. P(i,j) is the probability that A wins; A needs i more wins to win and b needs j more wins to win. At the begin the...

I do not if it is the right section, however hello I'm Antonio and I am Italian so I apologize for my English. I have a problem I'm trying to manage a mathematical modeling from a graphical point of view, (I applied chaos theory and the theory of earthquakes and using the concept of point...

Hi there. I've got issues. Big ones. I need to simplify this crane structure, and calculate the strength on cilinder |c1c2| when applying a vertical load on the crane's hook. The purpose of this is to find how much of the strength is absorbed by the first cylinder (and possible the second one...

Ok-I'm actually looking to settle an argument on another forum. I have turbocharged my 1979 Volvo 240, and converted to a later style motor. Instead of drilling and tapping the boss in the block for my oil return to the oil pan, I welded a 1/2" NPT bung into my oil pan. The approximate inner...

Hi I am solving some problems in fluid dynamics I came to this problem that I don't understand how to solve it. A piece of granite floats at the interface of mercury and water contained in a beaker (Fig.). If the densities of granite, water and mercury are ρ, ρ1 and ρ2 respectively, the...

Hello, I am trying to create a subsystem with parameters shown here: I want the parameter name to auto-populate the 'Timer Name' in the blocks of Data Store Memory/Read/Write, but it just leaves it as 'nam'. The subsystem blocks are shown below. So basically, I was to set the Timer...

I have attached another diagram, and in the diagram I show a round piston with a 1 sq ft surface area pushing water through the pipe out into to open atmosphere at 14.7 psi at a constant velocity of 75 ft/sec. There is a vacuum behind the piston, and I have calculated a 37.9 psi dynamic pressure...

Hi! Can anyone recommend a text that goes through calculation in fall time, rise time, saturation time and final rise time thoroughly with some examples provided? I've looked through microelectronic circuit design by Jaeger / Neamen, they briefly mention the concept at best but do not have...

Hi, I have these equations which represent the car steering angles and velocity, but I could not understand how do the operate.They are used for continus turning motion without keeping track of the car angle Beta. I would like some hints if anybody is familiar with them or have any other...

I'm having problem to solve this problem in DP: Given 2 subsequences: X = {x1, x2,..., xm} and Y = {y1, y2, ... , yn} so `n <= m` and also `y1 <= y2 <= ... <= yn`. The goal is to find a sub-sequence of `X` (xi1, xi2, ... , xin) such that: sum(k is 1 to n) | xik - yk | is...

I am disappointed by the fact that receiver noise seems to be directly proportional to bandwidth. With a raised cosine shaped pulse transmitter the bandwidth is the more or less the reciprocal of the pulse duration. Short pulses mean large bandwidths and that means greatly reduced range, at...

In a project I'm working on at school I could only get static acceleration from the 3-axis accelerometer I have (MMA7361L). I used a simple set-up (4 pins: Tx, Rx, power and ground). As far as I understand, accelerometers are able to detect both types of acceleration but I don't know why I...

Circle Rolling around Rolling Circle (1) Circle 1 rolls around inside of the fixed base circle. Circle 2 rolls around inside of Circle 1.

How do we solve optimization problems with infinite horizon. I tried to look online for some guidance but nothing but just problems and no solution methods. For example how can I solve: maximize a_t \in[0,1] \sum\frac{-2a_t}{3}+log(S_T) where sum goes from 0 to T-1 subject to: s_t+1 = s_t...

Homework Statement Determine the power of a windmill using constants where appropriate.Homework Equations P = Fv K = (1/2)mv2The Attempt at a Solution Dynamics Method P = Fv In time Δt, Δm amount of wind passes through the windmill, at speed of v. Δp = vΔm = v(AρΔx) Dividing both sides...

Please cana nyone physically explain the meaning of Guyan reduction for dynamic analysis? I have an ide that it relates to the erduction in the degreeso f freedom of the structure for FE analsysis such that the model is still accurate but performs (in relation to the time required for completing...

Hello, I am trying to do the following: for i=1:3 semilogy(plot1,'r(-,:,d)',plot2,'b(-,:,d)',plot3,'k(-,:,d)'); legend('i legend1','i legend2',''i legend1'') end where I need to draw the same plots under different settings, such that each function has the same color under the...

Okay, I have read all the threads on this site that I could find about Bernoulli's equation and blood pressure, but I am still really confused, and the more I think about it the more confused I get. I get that bernoulli's doesn't take frictional losses into account, but at a short section of...

This is a fundamental question but will be grateful if helped. Please can anyone explain the effect of damping on frequency? Whether, damping increases or decreases the frequency and why? An explanation with a physical interpretation will be gratefully appreciated. Vishal

Does anyone have any suggestions on existing technology to solve air dynamic issue for rocket? Thanks in advance for any suggesitons

Homework Statement Trying to maximize the profit of a farmer using dynamic optimization. Each period the farmer has a stock of seeds. He can plant them at a cost c per seed or sell them for p. Every seed that is planted produces \gamma seeds for next period. In period m there is no longer any...

Homework Statement I'm having trouble understanding dynamic programming as it relates to sequence alignments. I understand from my lecture notes that the scoring matrix used has arbitrary values (in our case +5 for match, -2 for mismatch, and -6 for gap). I therefore understand why square...

Hi everyone, I'm trying to solve a problem concerning steady state and dynamic models of chemical reactor. I attached the problem statement for better understanding. Please disregard part (a). Here's what I have come up with so far: For part (b) I have the following From Mass Conservation...

In an air supply duct after the fan static pressure is maximal directly after the blades and is zero at the duct outlet, volume flow is minimal after the blades, maximal at the outlet. mass flow is equal at all points, speed of air constituents is minimal after the blades (where air is being...

Good afternoon, I've tried to find a simplified model for the dynamic forces acting on a rolling wheel, but have had very limited success. I'm looking for a force that is proportional (or related to) the rotational velocity of the wheel (rotational damping) because of the contact point of the...

Homework Statement A prismatic bar (with flange on bottom) has length L, diameter d (so A=(pi/4)d^2), and modulus of elasticity E. A spring of stiffness k is installed at the bottom of the bar (on top of flange). A sliding collar of mass m drops from a height h (above the top of the spring)...

Hi all I am trying to run an executable compiled from some Fortran files (not my own), which look like they are written in Fortran 77. One of these includes some dynamic space arrays, where the number of elements depends on an integer value passed to the subroutine, e.g. subroutine...

REWRITTEN: Well if you're interested I have a tank (actually a PVC tube with an end cap) that has an interior diameter of 86 mm. It stands on its circular face. Coming out near the bottom of the tank at a right angle is a metal pipe 11 mm in diameter (interior) and 312 mm long (in total that...

Hi all, I've created a structure containing various fields of data. The data in these fields is stored in matrices and is be added to at regular intervals. I'd like the system to identify the amount of inputs the fields already contain and then extend said matrices to include this new data...

hi i am new to fluent and i hav done few basic tutorials in fluent.But now i need to use dynamic meshing for my project so can anyone guide me how should i start to learn dynamic meshing. thanxxxxxxxxxxxxxx in advance

Homework Statement Assume a ball has mass "Me" and wrapped by water like ocean and Earth ,the water has mass "Mw" and density \rho ,when the ball spin with angular velocity \omega ,and the shade of system goes to ellipsoid, please expres the water depth in spherical coordinate system Homework...

Hi guys, I have a scissor linkage and I should calculate the force F for keeping the system in equilibrium in a specific position. The force must be applied in the the middle joint as you can see in the following picture: http://imageshack.us/photo/my-images/810/scissordisegno.png/ L...

I am intrigued by the idea of changing/dynamic transition probability matrix instead of the assumption of constant transition probability between states. For eg. Probability of population migrating between 2 states might not remain constant and can be a function of its population or some...

Dynamic pressure, from Bernoulli's principle, for a moving fluid with a given density is P = \frac{1}{2}\rho {v^2} On the other hand, we can compute the force on a plate hit by that fluid from the rate of momentum transfer. Assuming that the fluid exits sideways after impact, we have...

Homework Statement We have a body V1, which is in contact over body V2 over a flat (i.e. planar) surface S. (The planar approximation can be considered a good one). Body V1 is moving, V2 is stationary. A normal force F exists between the bodies at surface S, acting in point P. This force...

i heard that fluid dynamics and thermo dynamics are the hardest subjects in mechanical engineering and physics, can somebody elaborate on this issue ?

When I read some heat transfer book, I got a problem. There are some numerical calculation methods in dynamic heat conducting in tube wall, but all the methods assume the temperature on one side of the tube and then calculate the temperature distributed in the wall. But are there some methods...

Homework Statement The displacement from equilibrium caused by a wave on a string is given by y(x, t) = (−0.00217 m)sin[(44.4 m−1)x − (728 s−1)t]. i need to find (b) number of waves in 1 m waves (c) number of complete cycles in 1 s cycles (d) wavelength (e)...

Homework Statement http://img263.imageshack.us/img263/1961/carslide.jpg In a car whose mass (m) - 2250 kg, and drives in a velocity of 98 km/h, the driver activates the breaks and causes the four wheels to lock, and the sliding motion of a car through distance d, till decreasing the velocity...

To the EE Forum, I am a new guy on this Physics Forum and this is my first post. I have downloaded a free software code, Finite Element Method Magnetics (FEMM) solver (see http://www.femm.info/wiki/Download) but it doesn’t work because FEMM is limited to solving low frequency electromagnetic...