Body Definition and 1000 Threads

Homework Statement I just saw the equation R=R'Ω (where ' is dot, or the derivative) in my notes (unorganized obviously), and can't remember what it stands for (rotation matrices?). Can somebody please tell me what this equations means thanks. I know R is some position vector and Ω is the...

I have to run a FEA analysis on a nozzle check valve body DN700... Its been to a professional engineer and he has completed the study so I am trying to do it myself to get to know the software better... I'm using PTC CREO 2 mechanica as the software... Attached find a picture of the valve...

Hi everyone, I have read a few different ways of looking at this problem, and it's one of those things where I am happywith the answer, just not how to get there using proper mathematics. My lecturer described this with some complex integrals involving E (but I'm not sure what that is!) but I...

I'm not sure which group this question really belongs to, so "general physics" sounds like a safe bet. This question was prompted by having listened to Neil deGrasse Tyson's more philosophical views about our nature and our connection to the universe, which are quite insightful. Most of...

Homework Statement A 180 lb man weighs 5 lb in water. What is his percent body fat? Assume that fat has a density of 0.90 g/cc and muscle has a density of 1.06 g/cc. Water has a density of 1.0 g/cc. Although we are given the weight in lbs, it is okay to work with it like mass (as grams) or...

hey everybody :) i am new here and i need ur help. I have to solve this problem for home work tomorrow.Topic is forces in the body. I attached it. I actually need help for the whole first question. thx u in advance. Please try to explain it not too difficulty. thanks u :) Homework...

Homework Statement A disk or radius b rotates about a rod in its center with a constant angular velocity, Ω. At the disk's edge A, a pin is attached allowing for a body to be attached an freely swing during the rotation. Determine the differential equation for the angle β between the attached...

Homework Statement A perpendicular force F acts on the tip of a thin rod of length L and mass M in the ij-plane which is not fixed. What is the translational and rotational acceleration of the rod about the center of the rod? Homework Equations At first it seems like an easy problem...

Homework Statement I'm having some trouble understanding "conceptually" the following problem (example 6.18 in Kleppner and Kolenkow.) A stick, initially upright, starts falling: find the speed of the center of mass as a function of position. Homework Equations Work-KE thm. for a rigid...

Homework Statement Suppose the ruler in procedure 3 is asymmetrical, balancing at the 60.2 cm mark. The ruler is now supported at the 41.3 cm mark, and a mass of 364 g is placed at the 26.2 cm mark. Find the mass of the ruler. The ruler is 1.00 m long. Homework Equations...

Homework Statement If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to energy loss by radiation. At night in a dry climate, the temperature of the sky can drop to -40°C. If you are lying on the ground with thin clothing that provides little...

A general example of a linked body is an object that is made up of rigid bodies joined together by pivots, such as hinges and ball-socket joints. If the pivots are frictionless, and I apply a force to one rigid body, how can I go about describing the subsequent angular acceleration of the...

Homework Statement Two bodies travel the same distance. One body travels half of the distance with the speed V and the other half with the speed 2V. The second body travels half of the time with the speed V and the other half of the time with the speed 2V. Which of the bodies has the higher...

Hi guys, I can't get my head around the centre of mass of a submerged body at all. the notes I've been given don't actually state how you calculate the centre of mass of the submerged body at all and just state it with no decernable pattern. I did assume that it was the centre of mass of that...

Homework Statement In the image below, calculate the center of mass (x-bar,y-bar) of the composite body. Homework Equations I've used all of the equations for area for the shapes needed (triangle, square, circle). The Attempt at a Solution I have attached my calculations and...

Strange title? Basically, a few days ago we got a dead rat in our ceiling, which is covered in insulation. Took a while to find it, but it got me thinking, how would you detect a dead rat body? If it recently died, I first thought you could use thermal imaging (aside from the expensive aspect)...

Homework Statement A 0.9 kg mass at (x, y) = (20 cm,20 cm) and a 2.0 kg mass at (20 cm,100 cm) are connected by a massless, rigid rod. They rotate about the center of mass. Homework Equations x=(m1*x1+m2*x2)/(m1+m2) y=(m1*y1+m2*y2)/(m1+m2) I=1/12*ML^(2) The Attempt at a...

i was reading about derivation of Euler's equations for rotational dynamics (john taylor, classical mechanics, chapter 10) when i got stuck on one of the reasonings essentially it refers to the moment of inertia tensor, since the tensor itself about a point is dependent on the position of the...

Homework Statement A small body is set on the surface of a smooth sphere at an angle of 45 degrees from the center. At this point the sphere is given a constant acceleration in the horizontal direction of 9.8 m/s/s. There is more in the question, but the goal is to find when the body will...

So I am writing a program in python to do RK4 for the two body problem. I want it to display a sphere moving around another. It currently displays one sphere for a split second and then it goes blank. Any suggestions? from __future__ import division from visual import * from visual.graph import...

[SIZE="4"]So I derived this equation for the net force/acceleration of a motorcycle on a flat surface. I believe this equation could practically be used for any rolling object. ƩF = Fp - μ*Fn - FD Where: FP is the force of the bike acting against the ground, tangent to the ground FD =...

Is there a way to predict the motion of a non-rigid body?

First off,I would like to apologise for not introducing myself. I have yet to find that certain part of the forum,but if the mistake was on my part,mods please direct me. Now to go to the real issue. This is something I've long "gotten over",meaning it was in the introductory lessons in...

Homework Statement Four point masses form a rigid body (they are connected by massless rigid rods) given the positions M1= 3kg (2m, 4m, 0m) M2= 2kg (1m, -4m, 0m) M3= 1kg (10m, 2m, 0m) M4= 5kg (-5m, 2m, 0m) Find: A) Moment of inertia of this system when it rotates about x axis B) Moment of...

Hi, When looking at a photo or sketch, I find it hard to take out the important bits and turn it into a freebody diagram. I am doing this question (pic attached). Im quite unsure how to even begin. I've though of a few ways to start analysing it. The first way analyses AD as a whole. And...

where is the biological clock in our body? how does it effect us?

Homework Statement Equate the expression for centripetal acceleration with the gravitational acceleration to show that the central parts of the galactic rotation curve are consistent with rigid body rotation. The attempt at a solution Say a star near the galactic center has mass m and the...

Homework Statement It's not exactly a homework question, just want to see if i have the right concept in drawing free body diagrams See attached Picture. In case 1, the object is fastened on plane x-z and the rectangular block is fastened to the T-block in y-z plane. Will the force be...

Homework Statement Hot oil, Hot water, Cold Oil, Cold water Homework Equations Upthrust according to flotation principle The Attempt at a Solution It will weight lightest when Upthrust by the fluid is highest, which should be cold water. Answer given was " cold oil".

I'm just learning how to use Ansys Workbench 13 to analyze static structures. I need to analyze the deformation of a simply supported beam with a concentrated force in the center vertically downward. I have a 3D model of this beam created in Solidworks. How do I create a force in the center...

Hello, Does anyone knows why rigid body does not exist.So in order to know its history which textbook can i refer to ? For example to know classical mechanics properly you have to go to Newtons book known as Principia. In order to know rigid bodies who should we refer.

Homework Statement If a body is charged by rubbing it, its weight a) may slightly increase of slightly decrease b) increases slightly c) decreases slightly d) remains constant Homework Equations The Attempt at a Solution I know weight is nothing but gravitational force...

Homework Statement One body of constant pressure heat capacity C_P at temperature T_i it's placed in contact with a thermal reservoir at a higher temperature Tf. Pressure is kept constant until the body achieves equilibrium with the reservoir. a) Show that the variation in the entropy of the...

Ok so I'm trying to show how a bullet in real life will not actually make a person fly backwards like it does in movies. I have some idea of how to go about this but need help. So far... I know it's a perfectly inelastic collision since the bullet sticks into the person so would I have to use...

Hello.. The query is regarding thermal conduction of heat from a solid body: Suppose we have a long metallic rod which is insulated on the curved surface and one of the bases. If we supply Q amount of Heat for a small time to the rod from the non-insulated end, initially the temperature of...

Homework Statement http://i.imgur.com/0h6dF.png Homework Equations ƩFx=0 ƩFy=0 ƩMo=0 The Attempt at a Solution not sure what unknowns are

Homework Statement https://dl.dropbox.com/u/66988308/Capture.JPG Homework Equations V=rWThe Attempt at a Solution I tried to plug in the forumla , and algebras but I keep getting rc/rf as answer instead of rf/rc as the book says. Work: Vf=(rf)W W=Vf/rf W=Vc/rc Vc/rc = Vf/rf (Vc)(rf) = (Vf)...

Hi guys, I'm working on one assignment about C-Spanner screw an impeller failure analysis. However, we're unsure if the free body diagram we draw is correct or not, given that our calculated safety factor is unreasonable. Can anyone give us a hand and have a look. Moreover, if someone can...

Homework Statement A 60 kg man stands in a 30 kg box on a light weighing machine. If the box is kept at rest due to force applied by the man by the rope , what is the weight shown by the weighing machine? Homework Equations The Attempt at a Solution .answer given in book is 15...

Homework Statement How would the free-body diagram of two 45 degree right angle wedges stacked on one another look like? (It is stacked so that the two wedges form a square) There is friction that is holding the wedges together. The wedges are in place and not moving. ___ |\ | | \| ----...

Homework Statement Identify all forces acting on the object and draw the free-body diagram. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other...

Homework Statement A force of magnitude F= 7.30 N pushes three boxes with masses m1= 1.80kg, m2= 3.00kg and m3= 4.20kg, on a level surface. Draw a free body diagram showing all the individual forces acting on the system consisting of boxes 2 and 3 together. Indicate the directions of the...

Homework Statement The picture attached is the problem. Also given is the constant acceleration of 2m/s^2, a frictional force of 75N, and the mass of block A is 25kg. Homework Equations The Attempt at a Solution I just need help with drawing the free diagram part involving the normal force...

In the figure below, m1 = 10.5 kg and m2 = 3.5 kg. The coefficient of static friction between m1 and the horizontal surface is 0.50, and the coefficient of kinetic friction is 0.30. I've drawn the free body diagram myself and labeled it but don't know how to structure the equations and stuff...

Homework Statement Now , I Will Begin by stating the calculation and i will post the query at the end. so here we begin, we know that If W is the work done by a conservative force, potential energy change is given by: ΔW= - ΔU ...(1) ie when work done by conservative force is positive...

Homework Statement Assume the system is massless. The Attempt at a Solution Here is my quick attempt at drawing a free body diagram for this system: What I am not sure about is the direction of the force at F. Should the force be A or B?

Homework Statement Much of the of heat lost from a cross-country skier's body is radiated from the head, since it is often uncovered. Treat a head as a 20-cm-diameter, 20-cm-tall cylinder with a flat top. If the surface temperature of a body is 35 C, what is the net rate of heat loss on a...

When a black body is heated the colors listed are IR, red, orange, yellow, white, blue-white, UV. Why doesn't a black body radiate all colors when heated: Red Orange Yellow Green Blue Indigo Violet? And why not shades of these colors?

Hi everyone! Which is the formula and the proof of the projection of the angular momentum of a rigid body along the rotation axis? I searched on the web and on my mechanics book but cannot find anything... does somebody know this curiosity ?

Hi I am making physics engine (computer) and i have some problems with interpretating multiple forces on one body. http://img837.imageshack.us/img837/396/75i7i47i6.png On the fourth car (on right) there are two forces acting on two rear wheels, interpretation is obvious, but what when...