Center of mass Definition and 899 Threads

  1. P

    Angular speed around a bar/clay system's center of mass after impact

    On a frictionless table, a glob of clay of mass 0.740 kg strikes a bar of mass 1.740 kg perpendicularly at a point 0.140 m from the center of the bar and sticks to it. If the bar is 0.660 m long and the clay is moving at 9.600 m/s before the impact, what is the final speed of the center of mass...
  2. V

    Center of mass, moment of inertia for x = y^2 and y = x - 2 with density d = 3x

    Here is the problem: A region is defined as being bounded by the parabola x = y^2 and the line y = x - 2. The density of this region is \delta = 3x. a) Find the center of mass. b) Find the moment of inertia about the y-axis. c) Find the radius of gyration about the y-axis...
  3. S

    Multiple choice ? on center of mass

    Two balls of masses m1 and m2 are moving along x-axis w/ velocities, v1>v2>0. After transforming from the lab frame to the center-of-mass frame, what are the velocities of m1, v1com, and mass m2, v2com? Vcom is the center of mass velocity for the system of both balls. The choices are...
  4. P

    Triple integral and center of mass

    A cone of height h and base radius r has density equal to distance from its base. Find it's center of mass. How do I write a function for the density? Is it p=h-z? And what are the limits of r if I want to do this in cylindrical coordinates? Thanks in adv.
  5. U

    Determining Maximum Distance Using Center of Mass

    question is http://home.earthlink.net/~urban-xrisis/clip003.jpg I'm guessing that the center of mass has to be in the edge. I'm not sure how to set it up so that I can find the most distance. any ideas?
  6. V

    Finding the Mass of a Suspended Necklace Using the Center of Mass Method

    Been trying this one using: x1m1 = x2m2 I guess I just maybe am not using the right mass or length for center of mass.. Here's the question: A 0.19 kg meter stick balances at its center. If a necklace is suspended from one end of the stick, the balance point moves 16.3 cm toward that...
  7. H

    Simple center of mass problem but i cant figure it out

    I feel silly for ask you for help on this simple center of mass problem but i got wrong answers... Where is the center of mass of a uniform, L-shaped iron rod of sides X = 0.8 m and Y = 0.5 m, respectively? Take the corner to be at (x,y) = (0,0), with the X and Y sides along those axes...
  8. U

    What Is the Acceleration of a Rolling Sphere Down an Inclined Plane?

    a solid sphere of mass M and radius R rolls without slipping down an incluned plane whose incline angle with the horizontal is 30 degrees. That is the acceleration f the sphere's center of mass? not sure how to attack this problem. Any equations and leads would be appreciated.
  9. G

    How Do You Calculate the Center of Mass for a Three-Mass System?

    I'm having a difficult time with this question, and I'm sure it's easy. The question is, find the center of mass of the three-mass system. Specify relative to the left-hand 1.00kg mass. Mass1 = 1kg Distance = 0m? Mass2 = 1.5kg Distance = .50m Mass3 = 1.1kg Distance = .75m I'm...
  10. W

    How Does a Circular Hole Affect the Center of Mass of a Rectangular Plate?

    A thin rectangular plate of uniform areal density 2.96 kg/m2 has length 42.0 cm and width 26.0 cm. The lower left hand corner is located at the origin, (x,y)= (0,0) and the length is along the x-axis. There is a circular hole of radius 5.50 cm with center at (x,y)=(15.00,11.00) cm in the plate...
  11. W

    How Do You Calculate the Center of Mass of a Parabolic Plate?

    A uniform plate of height 1.59 m is cut in the form of a parabolic section. The lower boundary of the plate is defined by: y=0.65x^2. Find the distance from the rounded tip of the plate to the center of mass. i tried to do this usin calculus and got the answer Ycm=1.01 which was wrong and...
  12. tandoorichicken

    What is the center of mass of a lamina with variable density?

    Any hints on how to approach this problem? A lamina occupies the part of the disk x^2 + y^2 <= 1 in the first quadrant. Find the center of mass if the density at any point is proportional to the square of its distance from the origin
  13. Z

    Spring Projectile problem: center of mass

    Hello everyone. I'm burning my head at this one, maybe someone could offer some insight? Here's the deal: imagine two masses, m1 and m2, united by a massless spring, of length l (relaxed). m1 | | _ > spring, at length l (relaxed) | ___m2____ ground The system has...
  14. U

    Equation for velocity of center of mass

    What is the equation to find the velocity of the center of mass? since... x_{CofM}=\frac{m_1x_1+m_2x_2}{M_{total}} then... v_{CofM}=\frac{d(m_1x_1+m_2x_2)}{dt(M_{total})} this means... if p=momentum v_{CofM}=\frac{p}{M_{total}} is this correct?
  15. B

    Finding the X Component of the Center of Mass of a Cut-Out Square Plate

    A uniform square plate L = 5.9 m on a side as a square section d = 2.5 m cut out of one side. What is the center of mass of the remaining plate? Use a coordinate system with origin (0, 0) at the center of the plate. The answer must be given in components. X = ? Y = ?. From the...
  16. D

    What is the concept of concentrated mass?

    A little confused, could someone explain what it means when it is said that "the point in a body or a system of bodies, at which the total mass of the body or system may be regarded as concentrated".(definition of Center of mass) What does it mean concentrated? I'm trying to understand the...
  17. T

    Find Your Center of Mass Solution: How Far Can You Move on a Floating Board?

    Part of my problem for physics is finding how far a person can move along a floating board. The board is not acted on by any outside forces so the center of mass before the person starts moving and the center of mass afterwards stays the same. Their is no air friction on the board. The Person...
  18. I

    Linear Density & Center of Mass

    Would anyone be able to give me a hint for this question? Do I take the integral? I have possible answers but I am unsure. A rod of length 30.0 cm has a linear density given by: D = 50.0g/m + 20.0xg/m^2 where x is the distance from one end measured in meters. a. What is the mass of...
  19. T

    How Does the Center of Mass Affect Distance When a Dog Walks on a Boat?

    The problem is a dog weighing 10lb is standing on a flatboat so that he is 20ft from the shore. He walks 8 ft on the boat toward shoare and then halts. The boat weighs 40 lb, and one can assume there is no friction between it and the water. How far is the dog from the shore at the end of this...
  20. T

    Finding Distance of Fragment After Shell Explosion - Center of Mass

    Although this seems simple, I don't think I'm reading the problem right. Currently we are studying center of mass such as the velocity and position of the center of mass. The problem is a shell is fired from a gun with a muzzle velocity of 1500ft/s at an angle of 60 degrees with the...
  21. S

    Center of Mass Problem: Treating Corrections

    I don't know how to treat a center of mass corrections. Suppose to have a Slater determinant of N single-particle wavefunctions. If I make a traslation to center of mass of system, this is mean to move all particle in the following way: R_i ---> R_i - (sum_j {R_j}/N) But how have I to...
  22. T

    Center of mass of a right triangle

    Hey guys. this is my first time posting. can anyone tell me how to calculate the Y component of center of mass of a right triangle?? Major help would be appreciated :-D please email me at fakedoublebassdrummer@yahoo.com
  23. T

    Center of Mass of a Right Triangle

    Hey guys. this is my first time posting. can anyone tell me how to calculate the Y component of center of mass of a right triangle?? Major help would be appreciated :-D please email me at [email address deleted]
  24. B

    Finding the Center of Mass of a Hollowed Out Sphere

    Hey guys, this is my first thread here. I'm just looking for a hint or two (no answer please). A sphere of styrofoam has radius R. A cavity of radius R/2 centered a distance R/2 directly above the center of the sphere is hollowed out and filled with a solid material of density five times...
  25. J

    Finding the Height of Remaining Soda at Center of Mass's Lowest Point

    A right cyllindrical can with mass M, height H, and uniform density is initially filled with soda of mass m. We punch small holes in the top and bottom to drain the soda; we then consider the height of the center of mass of the can and any soda within it. If x is the height of the remaining soda...
  26. P

    Calculate the position of the center of mass of the weighted wheel

    A thin 8.0 kg wheel of radius 28 cm is weighted to one side by a 5 kg weight, small in size, placed 10 cm from the center of the wheel. (a) Calculate the position of the center of mass of the weighted wheel. choosing the 8.0kg wheel to be on the origin, my cm is (8.0*0+5*0.1)/(8+5)...
  27. B

    Find Distance from Base to Center of Mass of Ladder

    A man of mass 83.8 kg stands on top of a uniform ladder whose mass is 11 kg and whose length is 8.7 meters. Find the distance (in meters) from the base of the ladder to the center of mass. Here's what I did: X(center of mass) = (83.8*8.7) + (11*0) / (83.8+11) = 7.69meters but the...
  28. L

    How Does Adding a Weight Affect the Center of Mass of a Wheel?

    A thin 6.0 kg wheel of radius 30 cm is weighted to one side by a 2.0 kg weight, small in size, placed 24 cm from the center of the wheel. Calculate the position of the center of mass of the weighted wheel. Here's what I have so far. I set the origin as the center of the wheel. Center of...
  29. E

    How Does Center of Mass Influence Collision Outcomes?

    PRoblem: A 4.00-kg block is traveling to the right at 5.50 m/s, and a second 4.00-kg block is traveling to the left at 4.00 m/s. Find the total kinetic energy of the two blocks in this reference frame. I did this by adding the two kinetic energies from the equation K =p^2/2m. It then asks...
  30. S

    Why Does the Spaceship Come to a Halt When Firing a Rocket?

    With the engines off, a spaceship is coasting at a velocity of +250 m/s through outer space. The ship carries rockets that are mounted in firing tubes, the back ends of which are closed. It fires a rocket straight ahead at an enemy vessel. The mass of the rocket is 1200 kg, and the mass of the...
  31. S

    Physics Hwk. Problem: Center of Mass

    With the engines off, a spaceship is coasting at a velocity of +250 m/s through outer space. The ship carries rockets that are mounted in firing tubes, the back ends of which are closed. It fires a rocket straight ahead at an enemy vessel. The mass of the rocket is 1200 kg, and the mass of the...
  32. P

    Where is the Center of Mass for a Semicircular Wire?

    A uniform thin wire is bent into a semicircle of radius r. Determine the coordinates of its center of mass with respect to an origin of coordinates at the center of the "full" circle. (The semicircle is in the positive y plane.)
  33. T

    What is the center of mass of a pyramid?

    I know how to find the center of mass of a 2 dimensional object like a piece of plywood or something like that, but when it comes to 3-D objects I'm clueless. All I know is Mx=x1m1+x2m2+...xnmn here is my problem, i don't know if i should split the pyramid into 4ths or not. The Great...
  34. T

    Help with problem of Center of mass, linear mass density and total mass

    Problem: The real problem is that apparently the professor explained this on monday and I didn't make it to the class. So really, any nudges in the right direction will be greatly appreciated.
  35. M

    What is the center of mass of the remaining part of the sphere ?

    Please who can solve this for me... :frown: Many thanx A solid sphere has a mass of 25 kg and a radius of 30cm. The center of the sphere is placed at the origin,x=0,y=0,z=0. The sphere is cut and the part of the sphere above z=7cm is removed. What is the center of mass of the remaining...
  36. Cyrus

    How Does the Center of Mass Remain Stationary During Constant Motion?

    Hi, I have another question on the center of mass this time. I read a problem in my university physics book by sears and zemanski which had a problem in which two guys want a mug of beer on an ice pond. There is a rope between them and each man tugs on the rope pulling themselves towards each...
  37. D

    Center of gravity (it's not center of mass )

    Center of gravity (it's not center of mass!) Hi, I'm a very desperate person right now. For two days (I'm totally dumb) I've been trying to calculate the center of gravity of two rigid bodys... Look, it's not the center of mass (I'm not that dumb!). OK, here's the problem...(at least one of...
  38. M

    Calculating Center of Mass of a Hollow Nose Cone

    I am working on a rocket and need to find the center of mass of a hollow nose cone. Any help would be appreciated.
  39. P

    Calculating Center of Mass for a System of Spherical Masses on the x-axis

    Hi, here is the problem: Imagine three spherical masses all fixed on the x-axis: mass 5M at the origin, mass 2M at x =+12.0 units, and mass M at x = -8.0 units, all connected by a rigid rod whose mass can be ignored. At what position along the x-axis is the center of mass of the system...
  40. PeteGt

    Center of mass and REduced mass

    I forget how these two relate both conceptually and mathematically...any help?
  41. S

    What is D in the Moment of Inertia Formula?

    Inertia and Center of Mass?? I'm a bit confused about finding the moments of Inertia for objects, I know I=Icm+MD^2 but what exactly is D, is it the distance from the Center of Mass to the pivot point, can someone please explain this to me? :confused:
  42. S

    Solving Center of Mass Prob: Stick Length 0.25m, Mass 0.53kg

    Can someone please help me with this problem, a hint, anything something? A girl throws a stick with a length of 0:25 m and a mass of 0.53 kg into the air in such a way that the center of mass rises vertically. At the moment it leaves her hand, the stick is horizontal and the speed of the...
  43. J

    Find Initial Acceleration of Rod's Center of Mass with Newton's 2nd Law

    here's the question: A uniform rod of length 1.15 m is attached to a frictionless pivot at one end. It is released from rest from an angle of 27 degrees above the horizontal. Find the magnitude of the initial acceleration of the rod's center of mass. So far I've only been able to figure...
  44. J

    Is this a center of mass question?

    Question: Find the solid angle subtended at the origin by a thin circular disk of radius a, whose cente is a distance b from the origin and where the normal to the disk is parallel. Do I have to find the center of mass to solve this question?
  45. D

    The center of Mass perfectly match the center of Force->

    In a system of several masses the center of force has same position with the center of mass in the geometrical space; Yes or No? Please explain why!
  46. S

    Finding the Center of Mass of a Uniform Semicircular Disk Using Integration

    Show that the center of mass of a uniform semicircular disk of radius R is at a point (4/(3*Pi))R from the center of the circle. well I know I am suppose to find this by integration. By this equation M\vec{r_{cm}}=\int\vec{rdm} But, I am not sure how to find dm in this case... do I...
  47. P

    Calculating Center of Mass for a Circular Hole in a Uniform Square Sheet Metal

    A circular hole of diameter 11.1 cm is cut out of a uniform square of sheet metal having sides 22.2 cm, as in the figure. What is the distance between the center of mass and the center of the sqaure? i need some serious help with cm, i don't get this at all.
  48. P

    Center of mass particle problem

    A 4.01g particle is moving at 1.36 m/s toward a stationary 9.43g particle. With what speed does the heavier particle approach the center of mass of the two partciles? i don't get how cm relates to finding speed The mass of a star like our sun is 347000 Earth masses, and the mean distance...
  49. C

    Finding the Center of Mass in a Divided Square

    Imagine a square with side length "a". Now, divide the square into 4 equal squares with side length "a/2". In the top righthand corner of the large square, a circle with radius "a/4" is cut out, which also removes the top corner piece. What is the new center of mass? (The origin is at the center...
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