bodies Definition and 523 Threads

Hello all. I'm trying to find the equation for combined Center of Gravity (CoG) when you combine two objects with different weight. I know how to find the centroid, which is what the CoG would be if both objects were the same weight. But what about two objects with different weight...

Say the gravitational force between two points is 80 N. The two points start off stationary. What do I do to find how those two objects would accelerate closer together? I'm trying to write a simple program that calculates the gravitational force between two objects and pulls them together, but...

I posed this question to my teacher: I have a 2 kg object and it sits at rest on the floor. The force is mass * acceleration, so it's about 20 N. Now I drop the ball from, say, 20 feet above the ground. Same mass, same acceleration, so it has the same force, 20 N; but we know the object hits...

Homework Statement A 2-kg block falls from rest a vertical distance of 0.75 meters above the top of a spring. The block lands on top of the spring compressing it 0.35 meters from its equlibrium position. a) What is the gravitational potential energy of the 2-kg mass just before it is...

It's often said there are no rigid bodies in relativity. Is the notion of "angle" primary or derived in relativity? Does "angle" require rigid bodies, at least "locally"? For example, to use light rays to measure the metric, do we need mirrors which are "rigid"?

Homework Statement One stellar mass is defined as the mass of our sun (1Ms = 1.99 x 1030 kg). ONe astronomical unit is defined as the length of Earth's semi-major axis (1AU = 1.49 x 1011 m). The star Epsilon Eridani in the constellation Eridanus has a planet (discovered in 2000) orbiting it...

Homework Statement A hollow cylindrical shell with mass M = 100 g and radius R = 5 cm rolls without slipping down an inclined plane making an angle \alpha = 30° with the horizontal. (a) If the initial speed of the shell is zero, what will be the speed of its center of (c) Calculate...

Homework Statement There is a slider-crank mechanism. Express the angular velocity omegaAB and angular acceleration alphaAB of the connecting rod AB in terms of the crank angle theta for a given constant crank speed omega naught. Take omegaAB and alphaAB to be positive counterclockwise. The...

Hi.I have some confusion on this question ...here is the question 1.A(n) 2.6 kg object moving with a speed of 7.9 m/s collides with a(n) 3 kg object mov- ing with a velocity of 7.4 m/s in a direction 56.1768◦ from the initial direction of motion of the 2.6 kg object.What is the speed of...

Homework Statement The Stardust spacecraft was designed to visit a comet and bring samples of its material back to the earth. The craft is 1.7 m across and has a mass of 385 kg. In January 2004, from a distance of 237 km, it took the photograph of the nucleus of comet Wild2, shown in the...

Homework Statement A ball is thrown from top of a 25m tall building. The balls initail speed is 12m/s. At the same instant a person is running on the ground at the distance of 31m from the building. What must be the avg speed of the person if he is to catch the ball at the bottem of the...

Homework Statement Two bodies A and B of mass m_1 and m_2 are connected via a spring of natural longitud l_0 and elastic constant k. Both bodies are free of net force until at an instant t_i something applies a constant force F to the body A, in the direction of B. (see the diagram)...

Homework Statement A ball is thrown straight upward and rises to a maximum height of 18 m above its launch point. At what height above its launch point has the speed of the ball decreased to one-half of its initial value? Homework Equations i don't know. The Attempt at a Solution...

I have a couple problems that I can't seem to get. The first I'm really close, I can tell, because my professor did one that was similar in class. The answer the book gives is 250 lbs, I'm coming up with 225. The second I think is similar to another problem he did in class but I'm not...

What happens if we apply on B a force bigger than the static friction with the floor and also bigger than the static friction with the upper body A, but smaller than their sum? Will B move? what about A?

<crackpot link removed> So what's up with them?

Does anyone know of a good mathematical reference covering the use of one-parameter group actions to model rotations of planets and/or other rigid bodies? Thanks in advance!

My boss and i were considering he following problem (see attached image): 2 unequal masses rotate an equal distance, r, about an axis. We both agreed that regardless of their angular position from each other (wether they were diametrically opposed or otherwise oriented, the 2 examples shown...

How would one go about calculating (as a first-order approximation) the gravitational time dilation generated by multiple point sources? When generated by one point source (M = 1\cdot10^{25}, r = 1, t = 1), I've got it down to: \tau = t \cdot \sqrt{1 - \frac{2GM}{rc^2}} \approx...

Homework Statement Two bodies mass m_1 and m_2 are a distance x apart. How long do they take to collide as a result of their gravitational attraction to each other. Homework Equations This question was asked in another thread which I found in a search. However the final answer was...

Homework Statement Hi. I am a newbie to the Physics forum. I am actually attempting to figure out a problem where there are two bodies forced to revolve around each other. The only constraints that would exist are the distance of separation between the two bodies is assumed to be constant...

Why do muscle cells have more golgi bodies than, say, cheek cells?

Hi I was ready a physics textbook and came across a quiz related to friction "What is the direction of the friction force on a crate which is on a truck moving towards east" . I think it is west, but I don't know if I am correct. As the crate is also moving with truck, the truck...

We all know this book... its is basically the SR as we know it. you can find it here ww.fourmilab.ch/etexts/einstein/specrel/www what i was looking for was how and on what basis back on 1905 the Albert figures out the speed of light is constant... all I get is this "Any ray of light...

Edit: Tried to post three times and forum kept adding the prompts. Removed Prompts. Homework Statement Three blocks are initially at rest on a level frictionless surface. At t=0s, a three identical forces are applied to a different point on each block. Each block is a rectangle approximately...

Do you know why potyviruses generate inclusion bodies as part of a translational strategy? I tried to find it on the web, but not many of them are that specific and hard to understand. thanks

So the situation is like this a ruler (of uniform mass) is pinned to a nail through its center. The has very little friction so it will spin but come to a stop. Initially it is at rest and is sitting perfectly horizontal (so that means the center of mass is at the center of the ruler). Now I...

Say you have 2 masses connected by a massless string, and another massless string is connected to the rightmost mass. A tension force T acts along this rightmost string, resulting in the string connecting the 2 masses to become taunt. In these cases, you can treat the 2 masses as one mass...

Two metal spheres (r2 = 2 X r1) have the same charge q on each of them separately. Now they are brought in contact. What will be the new charge distribution? My extension : What are all the factors that determine the new charge distribution? What if they are connected by a metallic rod...

Hello! The stem from this problem came to me when I was pondering how to describe the motion of two massive objects feeling the others' gravitational attraction (i.e binary star systems or something like that). Well this got ugly fast so I had to simplify a lot of things, and I finally got an...

Homework Statement Two bodies move in a straight line towards each other at initial velocities v1 and v2 and with constant retardation a1 and a2 respectively at the initial instant. What is the max initial separation between the bodies for which they will meet during the motion? (sqr ->...

According to my book the electric charge of large bodies like the Earth and the moon is pretty close to zero. But the Earth has poles and a magnetic field, which suggests that it isn't uniformly distributed at all. These two things SEEM contradictory to me, what is it that I am not getting? k

Hi, I was just going over some equations for velocity with respect to bodies revolving around the sun. I wanted to figure out the ratio of tangential linear velocity (i.e. speed) of a body when it is at its perihelion to its velocity at aphelion. In other words, I wanted to solve for...

So I'm trying to research all the bodies homeostatic responses to excercise. I have temperature and the details of what happens there but I am struggling to find information on , Energy (glucose), Respiration and blood pressure. Also am I missing any other items here? And does anyone know of a...

Problem Derive Euler's equations of motion for a rigid body from the Lagrange formulation (for generalized coordinate \psi, the third Euler angle). Applicable Formulae Euler's equations of motion (what we are trying to derive) are: I_{1} \dot{\omega_{1}} - \omega_{2} \omega_{3} (I_{2}-I_{3}) =...

I read that charge resides on the outer surface of a charged (electrically) body. Is it meant only for charged conductors or all charged bodies including conductors or insulators? What are the specific points with respect to conductors and charges other than (i) conductors allow current freely...

Hi, I have to solve (using numerical methods) fallowing problem: there are for example three pointed bodies in 2D. I have to find trajectories of their motions in their own gravitational field. In cartesian coordinates for each body and direction I write equation of motion (that gives me system...

Forgive me if this is a noob question. I know there are no perfectly rigid bodies so that if you had a light-year long rod and pushed it, the other end would not move immediately because if it could, then information could be transmitted FTL. But, what if you pushed on a quark in the same...

how heat will transfer in fast moving bodies?

Working on some sci-fi and exploring the theory that there is redundancy in the human body, i.e., we could function with fewer cells, then fewer amounts of elements, and therefore less matter. Could we be “fine-tuned” and exist as a smaller version of ourself?

yeah that's what I call body heat! :smile: http://www.upi.com/NewsTrack/Quirks/2008/01/07/crematorium_plans_to_create_body_heat/4593/

How does heat tranfer in motional bodies? Homework Equations The Attempt at a Solution

Is it a myth that the bodies resistance to germs be "built up" by exposure? I'm not sure is this is more a medical question, but I'm thinking it's more of something biologists would address? When I see people criticized about eating things that have come into contact with unclean or doing...

[SOLVED] center of mass Homework Statement 2 bodies m1 and m2 are hanged from the ceiling with a thread with length L. the bodies are also connected to one another with a thread which length is equal to the length from the masses to the hanging point. around that thread there is a spring...

There is a point b/t the Earth and the Moon where the gravitational effects of the 2 bodies balance each other. How far apart from the center of the Earth is this point? Answer: x = 3.44 x 10^8 m (from the earth) or 3.82 x 10^7 m (from the moon). I have no clue what to do. I assume you would...

Homework Statement Does it make sense to talk about kinetic energy without specifying, which axis the body is rotation about? I mean, since K = ½ * I * w^2, I have to say that " ... the kinetic energy of the body around the x-axis is ...", right?

Homework Statement Ok, when talking about rotating bodies, we deal with the following accelerations - please correct me if I am wrong: A radial acceleration (a.k.a. the centripetal-acceleration): w^2*r or v^2/r. An angular acceleration given by dw/dt. A tangential acceleration given...

Homework Statement A triangular body changes orientation as the suspporting links rotate. At the moment shown, theta = 90 deg, theta_dot = 5 rad/s, and beta = 45 deg. Determine vA and the angular velocity of the triangular body. rB/C = 2j cm and rB/A = 5i cm Points E and D are fixed...

Homework Statement Point O is fixed in space. Gear 1 has an angular velocity of 20k rad/s, and Gear 2 has an angular velocity of -10k rad/s. r1 = 0.3 m and r2 = 0.2 m. What is the angular velocity of the connecting arm OA, and what is the speed of A? Gear 1 is larger than Gear 2. Gear 1...

Help me...PLEASEE.. I would like to know about: 1)Background/History:Kinematics of a rigid bodies - linear and angular velocity 2)Application Kinematics of a rigid bodies - linear and angular velocity in dynamics Please reply me A.S.A.P =(