Dynamics Definition and 1000 Threads

Conventional Cosmology would explain greater than c recessional velocities of the nebula as a non-problem regarding STR because the luminous matter is co-moving with respect to local space rather than with respect to local space (the latter generally referred to as peculiar motion). In an...

Homework Statement The problem is in the photo below: https://www.physicsforums.com/attachment.php?attachmentid=71928&stc=1&d=1407288108 Text: Figure CP6.74 shows an accelerometer, a device for measuring the horizontal acceleration of cars and airplanes. A ball is free to roll on a parabolic...

Homework Statement A block of mass m is at rest at the origin at t = 0. It is pushed with constant force Fo from x = 0 to x = L across a horizontal surface whose coefficient of kinetic friction is μk = μ0(1 - x/L). That is, the coefficient of friction decreases from μ0 at x = 0 to zero...

I am a B.Sc. 2nd year student of Maths (Honours-equivalent to an US Maths Major), Physics and Computer Science(Probably equivalent to US Physics minor and CS minor) in a college in India. I hope to become a specialist in Mathematical Physics later on. Since my background knowledge of core...

Homework Statement It is given in the photo Homework Equations They are all given in the photo The Attempt at a SolutionI solved exactly the same as in the solution manual, except for the FBD of the slider B, when they write the 2nd Law, they do not input the weight there, only the...

can someone explain this problem step by step (not a homework problem, just an example i found and i want to see how its done). a hot wet summer is causing a mosquito population explosion in a lake resort area. the number of mosquitoes is increasing at an estimated rate of 2200+10e^(0.8t) per...

Homework Statement A rocket nozzle is operating with a stretched out throat, (L = 50 cm and D = 10 cm). If the inlet stagnation conditions are po1 = 1 MPa and To1 = 1500 K, determine the nozzle exit velocity and mass flow for a back pressure of 30 kPa. The diameter of the nozzle at the exit...

Hi all, I need help with numerical solution of motion equation. From the numerical point of view and in the real of the finite element method, which method is recommended for the solution of damped ( proportional damping) linear motion equation? I have been trying three common methods; Modal...

Take a closed system of particles. Each has it's own mass, but that's really about it for the sakes of this argument. Now suppose there is some standard force law that applies between particles, whatever it may be. (In general it will depend only on the separation between particles and thus be...

Homework Statement A small body A is fixed to the inside of a thin rigid hoop of radius R and mass equal to that of the body A. The hoop rolls without slipping over a horizontal plane; at the moments when the body A gets into the lower position, the center of the hoop moves with velocity v0...

Homework Statement A canon fires a projectile at a speed of 100 m/s at angle of 20 degrees. (a) what is the radius of curvature of the projectile at its highest altitude? (b) What is the radius of curvature of the path .5 seconds after firing? Homework Equations Velocity vector = s'ur...

Hello everybody, Last semester I took dynamics and I got FD, and luckily the course is going to open in the summer school too.So I am trying to pass the course in the summer school, why not getting a good grade too. Reasons why I did not pass were mainly because I did not like the teacher (...

Can anybody suggest some basic models or problems in non linear dynamics on which an undergrad student can work on.

Hi everyone: I just started to learn special relativity but totally being confused about "velocity", "momentum" and "force". 1. The relativistic momentum is defined by "rest mass * ordinary velocity * gamma". There are 2 kind of explanations. The first one is combining "rest mass * gamma"...

Homework Statement A cylinder of mass M and radius R, with moment of inertia: I_c = \frac{1}{2}MR^2 rolls down without slipping through an inclined plane with an angle of θ, while pulling a block of mass Mb with an attached frame (of insignificant mass) which is connected to the axis of...

My friend is trying to reproduce a research paper calculated using the CFD(computational fluid dynamics) software package star-CD sold by CD-adapco, but so far he failed, what can he do? Here is the paper he is trying to reproduce: Endothelial Cell Layer Subjected to Impinging Flow Mimicking...

Homework Statement Two blocks of masses m1 = 8.00 kg and m2 = 12.00 kg are connected by a string of insignificant mass. The string lies on a cylinder of mass 0.50 kg and a radius of 0.15 m. The coefficient of kinetic friction between m1 and the surface of an inclined plane is 0.10. The angle...

Homework Statement Hi everyone! I'm struggling to understand how to solve this problem, I searched on the web, but I didn't find anything similar. I have a motor delivering a power P=5kW at n=1500rpm. This motor is mounted on 4 supports, each having a rigidity k=15kN/m. I know that distance...

https://scontent-b-sjc.xx.fbcdn.net/hphotos-xap1/t1.0-9/10373973_306663899490733_8092061444466097264_n.jpg

Attempt solution Y=(vsinø)t-0.5gt^2 4=(vsinø)t-4,9t^2 But there is 3 variables! Another eq is X=(vcosø)t 6=(vcosø)t But i did not found any away to solution

Homework Statement A light string is wrapped around a solid cylinder and a 300g mass hangs from the free end of the string. when released, the mass falls a distance of 54cm in 3.0s. a) Calculate the tension in the string. b) Calculate the mass of the cylinder. Homework Equations...

Please look at pictures. I do not understand the solutions; Here is how I find length of string: 5m/s*1.2s/rev=6m/rev=circumference=2piR R=0.95m. For the force: T=mv^2/r= 0.350 kg *5^2/0.95= 9.21N They got 9.16N?

Homework Statement A water droplet condenses at r0=0.80 m. The turbine is rotating at a fixed speed of N RPM. You can treat the water droplet as a point mass of m=0.002 kg. Starting from rest at its formation point, it starts moving outward on the radial vane as shown. Its mass stays...

Please look at pictures. Weirdly, my textbook does not give the answer to this question. Can you check my answer? Sorry for the really bad writing. If you ask, I can more clearly write it.

Suppose the energy density of the cosmological constant is equal to the present critical density ε\Lambda = εc,0 = 5200 MeV m-3. What is the total energy of the cosmological constant within a sphere 1 AU in radius? My answer: ε\Lambda = ET / V ET = ε\Lambda * V = (8.33 * 10-10...

A ship, on which airplanes land, has an airstrip of 70 m. The ship uses three different techniques to stop airplanes when they are landing. The first technique is to use a cable reel of radius 0.4 m, around which a non-elastic rope is coiled. The reel is to be rotated about its axle - which is a...

A piece of stone of mass m is rotating at constant angular speed ω in the vertical plane about the point O as shown in the figure. A rope of length R connects the ball to O. If the rope breaks when the stone is at A, calculate how long it takes before the stone falls back to the same level...

Homework Statement Arlene is to walk across a “high wire” strung horizontally between two buildings 10.0 m apart. The sag in the rope when she is at the midpoint is 10.0°, as shown in Fig. 4–47. If her mass is 50.0 kg, what is the tension in the rope at this point?Homework Equations The...

Hey guys, I've been wracking my brain for a while, and thus I have landed here yet again. My problem is the following: Say you have a pipeline with a venturi injector, and intermittently a large tank of water with a portion of air on top -- I.e. a closed circuit communicating between the...

Hi, am having a few problems applying bernoulli's equation when an electric pump is involved. I have attached a picture of the question. I understand how to apply bernoullis for venturi and pitot tubes but when it involves work being done on the system eg. a water pump, fan exhaust I don't know...

Hi folks! My system dynamics teacher gave us a couple of assignments to work out, there is one though that I can't seem to work out properly. Now I am aware that this is maybe not the correct part of the forum, but I didn't know where else to put it. I would love to see one of you guys...

Edit: Nevermind

I've recently heard of an analogy between fluid dynamics and electromagnetism in which the velocity flow field is identified with the magnetic vector potential, (and therefore the vorticity is identified with the magnetic field), and the vector \omega \times v is identified with the electric...

Homework Statement A 100 kg slender rod is lifted on the left end until the angle between the ground and the right end is 30 degrees. The right end is still in contact with the ground. The coefficient of friction between the rod and the ground is .5 and the length of the rod is 2.1 m...

There's a figure that comes with the question but I'm having trouble attaching it so I will describe it the best I can. There is a large cylinder labeled the reservoir. A horizontal pipe is connected near the base of the reservoir and it is open at the other end so fluid flows out (point B)...

I'm reading about the Principle of Least Action. As a prelude to it, we look at the functional J(x)=\int f(y(x),y'(x);x) dx where the limits of integration are x_1 and x_2. We want to find the function y(x) that gives the functional an extremum. Now, to do this, we write any possible function...

I'm going to run through a derivation I've seen and ask a few questions about some parts that I'm unsure about. Firstly the theorem: For every symmetry of the Lagrangian there is a conserved quantity. Assume we have a Lagrangian L invariant under the coordinate transformation qi→qi+εKi(q)...

Please see picture. Here is my method. Is it good? T=m2g m2g=m1a a=m2g/m1 -n+Fpush=Ma. (n=normal force of m2 on M). n=m2a=(m2)^2g/(m1a) -n+Fpush=Ma. Fpush=Ma+(m2)^2g/m

If I have say a stationary rod, and a particle collides with the rod whilst moving at speed v at the top end, why does the rod then proceed to rotate about the centre of mass of the system (whether that be in an elastic or completely inelastic collision where they both stick together). I...

I am needing assistant on my physics homework. I have received the answer of 0.6m/s2 and 0.9ms/2 for the answers but when i check my key that the answer provided it is 3.6m/s2 and when i check over the work they provided it doesn't make sense to me at all. They got the answer of 3.6 by adding...

PDF: http://www.aapt.org/physicsteam/2014/upload/exam1-2014-2-2-answers.pdf Homework Statement A disk of moment of inertia I, mass M, and radius R has a cord wrapped around it tightly as shown in the diagram. The disk is free to slide on its side as shown in the top down view. A constant...

Hi, I have an exam soon. This is urgent. Can you check my answer? A box with mass 100kg is being pushed with enough force such that a second box with mass 2kg does not slide down and the two accelerate to the right together. If us=0.5 and uk=0.1, what is acceleration minimum such that box m2...

Hi, There is something weird here: Please look at problem and solution. When I set my equations: 2000a=2000gsin(30°)-T 1800a=-1800gsin(20°)+T I add them up: 3800a=2000gsin(30°)-1800gsin(20°) a=1m/s^2 Now I want to equilibriate the car: The force of brakes=-2000a=-2000a=-2000N...

Homework Statement 1. A small pebble of mass 50g is dropped into a pond and falls vertically through it with an acceleration of 2.8ms^-2. Assuming that the water produces a constant resistance, find its magnitude. 2. A lift of mass 500kg is lowered or raised by means of a metal cable...

Homework Statement A homogene rod with length "l" is placed vertically, and a nail is stabbed on the top of the rod (now the rod has an axis). And then an impulse is given on the rod with the separation between the impulse given to the rod's axis is "d". Earth gravitational acc is represented...

A homogene rod with length "l" is placed vertically, and a nail is stabbed on the top of the rod (now the rod has an axis). And then an impulse is given on the rod with the separation between the impulse given to the rod's axis is "d". Earth gravitational acc is represented as g, the mass of the...

Hello all, I was thinking about situations in introductory courses or textbooks where pressure or buoyant forces are suddenly introduced in situations where they become relevant which lead me to think about the consequences of neglected said forces in more elementary problems. I'm curious as...

Homework Statement a) A 1.5 kg frog sits at rest on top of a solid disk. The disk's mass is 4 kg, its radius is 1.25 m, and it rotates on a frictionless axle. The frog jumps from the disk at 3.7 m/s at an angle of 50°. Find the angular momentum of the frog about the axle as it leaves the disk...

two masses, each of 400 kg, connect with a thin cord and pull up a plane inclined 30 °, as shown in Figure The coefficient of friction between M and the, inclined plane is 0.5; the coefficient of friction between M2 and the piano is negligible. (a) determine the acceleration of the system and...

Homework Statement A hard drive consists of a rigid circular platter (or disk) of radius 0.05 m and thickness 0.002 m. In normal operating conditions, the hard drive spins at 7200 rotations per minute. The read/write head is a light metallic element that floats just above the platter and both...