Center of mass Definition and 916 Threads

Suppose I give you a curve f(x) = \sin^2 (x) + ln(x) And suppose I tell you to rotate this curve about the x axis, we get disks. Now, I ask you, what is the center of mass of this object? Now immediately, you could say that \bar{y} = 0 because it is symmetric about the x-axis. I don't...

Homework Statement Find the center of mass of a triangle with two equal sides of length a. The triangle's third side is length b and it has a uniform mass of M. Homework Equations R = \frac{1}{M} \int dm \vec{r} dm = \frac{M}{A} A = \frac{1}{2}base*height The Attempt at a Solution...

Homework Statement I have to find the velocity of center of mass of a elastic collision. Momentum: Ball Ai = .23 J Ball Af = .06 J Ball Bi = .02 J Ball Bf = .19 J Am I correct in saying that all you have to do is you take the total momentum of both balls and divide by the...

Homework Statement Hey all. Below is the question and picture related to it. "Three uniform metre sticks each of mass M are attached together as follows: Stick 1 lies along the y-axis from y = 0 to y = 1.0m. Stick 2 lies along the x-axis from x = 0 to x = 1.0m. Stick 3 makes an angle of 60...

Velocity and Center of mass question? Homework Statement Having some issues with this one. "Ball A has a mass of .200kg and a velocity of 1.50 m/s. Ball B has a mass of .300kg and a celocity of -0.400 m/s. The balls meet in a head on collision. After the collision, the velocity of ball...

On a horizontal air track, a glider of mass m carries a post shaped like an inverted "L". The post supports a small dense sphere, also of mass m, hanging just above the top of the glider on a cord of length L. The glider and sphere are initially at rest with the cord vertical. A constant...

Homework Statement Let D be the upper half of the disc x2+y2 ≤1(that is, the part of the disc with y ≥ 0). Suppose the lamina Ω fills the region D, and has density given by ρ(x, y) = |x|. (a) Calculate the mass of the lamina. (b) Find the coordinates of the center of mass of the lamina...

Homework Statement A person with mass m1 = 69 kg stands at the left end of a uniform beam with mass m2 = 108 kg and a length L = 2.5 m. Another person with mass m3 = 67 kg stands on the far right end of the beam and holds a medicine ball with mass m4 = 9 kg (assume that the medicine ball is at...

Homework Statement Set up intergral expression for center of mass of a cone using cylindrical coordinates with a given height H and radius R Homework Equations rdrddθdz is part of the inter grand. M/V=D volume of cone is 1/3π(r^2)H The Attempt at a Solution dm=Kdv dv=drdθdx K...

Homework Statement In the 1968 Olympic Games, University of Oregon jumper Dick Fosbury introduced a new technique of high jumping called the "Fosbury flop." It contributed to raising the world record by about 30 cm and is presently used by nearly every world-class jumper. In this technique...

Im trying to figure out the center of mass of a cone for this research I'm doing. How do I find the center of mass of a cone?

Homework Statement Three ice skaters are on a perfectly smooth frictionless lake. They are together at rest at the middle of the lake when they push off on each other. When skater #1 (m1 = 80 kg) is 6.00 meters EAST of the starting position, and skater #2 (m2 = 60 kg) is 6.00 meters NORTH of...

Find the x and y coordinates of the center of mass of a flat triangular plate of a height H =17.3cm and a base B = 10 Cm Homework Equations Area = A = 1/2bh x = 1/A ∫ x(f(x)) y = 1/A ∫ 1/2((f(x)^2) The Attempt at a Solution Area = 1/2(10)(17.3) = 86.5 f(x) = 17.3-1.73x or...

1. A bumper car with mass m1 = 105 kg is moving to the right with a velocity of v1 = 4 m/s. A second bumper car with mass m2 = 98 kg is moving to the left with a velocity of v2 = -3.8 m/s. The two cars have an elastic collision. Assume the surface is frictionless. 2.Vcm= (m1v1+m2v2)/m1+m2 V1 in...

Figure 12-52a shows a horizontal uniform beam of mass mb and length L that is supported on the left by a hinge attached to a wall and on the right by a cable at angle θ with the horizontal. A package of mass mp is positioned on the beam at a distance x from the left end. The total mass is mb +...

A solid uniform disk of mass 19.0 kg and radius 70.0 cm (.7 m) is at rest FLAT on a frictionless surface. A string is wrapped around the rim of the disk and a constant force of 35.0 N is applied to the string. The string does not slip on the rim. The string is being pulled. When the disk has...

Homework Statement A very massive object with a velocity "v" collides head-on with an object at rest whose mass is very small. no kinetic energy is converted into other forms. Prove that the low-mass object recoils with a velocity 2"v" use the center-of-mass frame of reference...

I have been thinking about how to come up with a function of time for the n-body problem. Later I found that there still is no function of time known for the n-body problem, but I am still not sure where the brick wall for everyone is because I am quite sure my understanding has hit from very...

Homework Statement find center of mass Homework Equations (r1m1+r2m2+...)/m1+m2+...The Attempt at a Solution cut into two pieces with one center at 2,5 and one 3,2. used each square on grid as one unit is that okay?

If someone is on a boat that rests in a placid river with negligible friction between the boat and the river ,, suppose that person moves a certain distance ,Does that boat move as well , if so why ?

A small square plank of oak floats in a beaker half full of water. The piece of oak is 7 cm on a side and 3 cm thick and floats on its side as shown in Figure P10.80. Density of oak 750kg/m^3 Density of water 1000kg/m^3 There were two parts to the problem, the first is: Find the location of the...

Homework Statement A 1000 kg horse trailer with frictionless wheels is sitting in a level parking lot. The trailer is 4 m long, and its center of mass is at its center. Its passenger, a 500 kg horse, breaks free from its stall at one end of the trailer and walks to the other end. How far...

Let p be a positive constant. Suppose that a random variable X has probability function f(x)=cxp(1-x) for 0≤x≤1. Find formulas for c, μx, and Var(X) in terms of p. I know Var(X)=∫(x-μx)2f(x)dx I know that I did not show any work so please just give me a hint (I'm not asking you to solve...

How can one calculate the center of mass of a system made of two photons? I know that they have zero rest mass so the first intuition is to say that they do not have any center of mass. However, I read about something called center of momentum which is defined as a frame in which a moving...

We have a sphere that its center of mass is not located in its center. suppose it has a mass of m. what we want to do here is to write its movement equations, using Newton's laws or lagranigian.by move ment we mean writing the equations if a) a force F acts on the body on a surface that is...

Homework Statement [PLAIN]http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys211/oldexams/exam2/sp10/fig3.gif A 4.0 kg circular disk slides in the x-direction on a frictionless horizontal surface with a speed of 5.0 m/s. It collides with an identical disk that is...

Homework Statement An amonia NH3 molecule in the figure has three hydrogen atoms, which form a equilateral triangle as the base of a pyramid. At the top of the pyramid is the nitrogen atom. The length between any two hydrogen atoms is 9.4x10^-11, the length from nitrogen to any of the...

I am a bit confused about a statement I read in my textbook saying the sum of external forces on a body is equal to the body's mass times the acceleration of it's center of mass. It seems to me if a long rod is suspended in the air by a string at its center of mass, and I tap the rod near one of...

We are learning about centers of mass now and it made me wonder, does the universe have a center of mass? If so , what is its meaning? Is it place where "big bang" occurred? Also, on a related note, could the fact that the universe is expanding at an accelerated rate be explained by a net...

Homework Statement A body of mass m, moment of inertia I, radius R is rolling (without slipping) upon the action of force F applied in horizontal direction at a distance x above center of mass (com). Prove that acceleration of com (a) = F[(1+(x/R)]/[m(1+(I/mR2)] Homework Equations F -...

Homework Statement Calculate the X_com of the cone of mass M in terms of quantities given in the picture. The density of the cone is uniform. See the attachments for the picture. Homework Equations The Attempt at a Solution When I did it I got X_com = (3L)/2 and I am...

Center of mass --chair and cylinders! Homework Statement Jane is sitting on a chair with her lower left at a 30° angle with respect to the vertical. you need to develop a computer model of her leg to assist in some medical research. if you assume that her leg can be modeled by 2 uniform...

I have an interesting question, that I've been struggling with for a while now, but I'm somehow messing it up. I haven't found anything on the internet (hard to search for something like this) so I'm wondering if any of you know something useful about it, or do better at finding the solution...

Homework Statement having some major derp problems. I can't seem to remember how to find moment of inertia about the COM of and object or even finding the COM for that matter. I need it to solve a Euler Lagrange problem Can someone give me an idea on the integrals to use and in what...

My textbook is giving awfully complicated formulas for centers of mass for actual objects (if they are a system of massive points, that's simpler for me.) Intuitively though, it just seems like it would be a weighted average?? So, If I have a solid metal cube, divided into two halfs...

Homework Statement I'm being given problems regarding the center of mass of a uniformly dense object, and I am told by the textbook to use: \frac{1}{V}\int x dV I have no idea what to do with that. I'm pretty sure I won't be learning anything about multiple variable integrals for two...

Homework Statement http://imageshack.us/photo/my-images/24/wtfdiagram.png/ Homework Equations The Attempt at a Solution I really haven't the slightest clue how to read this diagram. I see nothing resembling a U.

Homework Statement A man with mass m1 = 60 kg stands at the left end of a uniform boat with mass m2 = 169 kg and a length L = 2.7 m. Positive x is pointing to the right. Assume there is no friction or drag between the boat and water. After the man walks to the right edge of the boat, what is...

Now i am suddenly confused with the concept of the center of mass. As we know , nucleus are a system of many-body,composed of nucleons. And their interactions are very complex between nucleons. I want to know, If we can observe a nuclei such as Ne20, how is the motivation of its center of mass?

Homework Statement A rod of length 36.00 cm has linear density (mass per length) given by λ = 50.0 + 21.5x where x is the distance from one end, and λ is measured in grams/meter. A. Find Total Mass B. Find center of mass from x=0 Homework Equations 1/M(integral)xdm , where M...

Homework Statement Homework Equations Please see attachment to #3. The Attempt at a Solution Apparently, the answer is Y= 4R/(3*pi). Why?

Homework Statement A binary star system consists of a star P and a star Q, of mass 4.0 x 10^10 kg and 2.0 x 10^10 kg respectively, separated 6.3 x 10^9 m apart. Star P and Star Q move in circular orbits with their centers at the center of mass which remains at rest. Find the position of...

I have been reading a number of papers on the biomechanics of running and they all talk about the center of mass (COM), but I haven't found any description of how to determine the center of mass. I understand, for instance, that the center of mass moves forward with more forward lean. The...

I was thinking that objects like a sphere have a center of mass in the middle of the sphere and also if you were in the middle of the sphere you would feel no gravitational pull in any direction. So then I was wondering if all objects had a zero gravitational pull at their center of mass. But...

Hello All, I am trying to create an experiment to determine the center of mass and inertia tensor of an aribtrary object. This object is small (softball size), and non symmetrical on all axis. I have some thoughts concerning gyroscopes and accelorameters, but am curious to see what thoughts...

As part of a problem I need to find the center of mass of a hollow hemisphere. I did it in the following way. I considered the lower hemisphere ( around negative z axis ) First by definition, the position vector of the center of mass is obtained as \vec{R}=...

Homework Statement A large wedge rests on a horizontal frictionless surface. A block starts from rest and slides down the inclined surface of the wedge, which is rough. During the motion of the block, the center of mass of the block and wedge. a. does not move. b. moves horizontally with...

Homework Statement The mass of the homogeneous flat plate is 50 kg. Determine the reactions at the supports A and B. I've attached the diagram. The Attempt at a Solution I know I will need to find the center of mass. I don't remember exactly how to do it, but I found the centroid...

Homework Statement A 1.0 kg rock is suspended by a massless string from one end of a 1.0 m long measuring stick. What is the mass of the measuring stick if it is balanced by a support at the 0.25 m mark? Homework Equations Torque=(distance perpendicular to force from the center of...

This is a pretty tough question for me. I am trying to learn, so please no rude people or trolls please. Here is the problem I was given. A 50 dyne steel rod is fixed at a point 20cm. from the right end. The clamp at this point provides a force of 200 dynes upward. The rod is in equilibrium...