Moment of inertia Definition and 1000 Threads

  1. M

    Mass Moment of Inertia: slanted solid parallelogram: Well past wit's end

    Perhaps Tensor Calculus holds the answer; but I just can't justify the time for studying that as I know nothing of it. The end objective is to calculate the mass moment of inertia of the yellow solid parallelepiped about rectangular axes through its centre of mass as in the diagram here...
  2. S

    Moment of Inertia for a Disk with Hole

    Homework Statement A uniform circular disk has radius 36 cm and mass 350 g and its center is at the origin. Then a circular hole of radius 7.2 cm is cut out of it. The center of the hole is a distance 10.8 cm from the center of the disk. Find the moment of inertia of the modified disk about...
  3. H

    Moment of Inertia & Angular Motion of a Stick

    A stick of uniform density with mass M = 7.5 kg and length L = 1 m is pivoted about an axle which is perpendicular to its length and located 0.12 m from one end. Ignore any friction between the stick and the axle. a) What is the moment of inertia of the stick about this axle? Iaxle = kg...
  4. E

    Moment of Inertia of a grouping of pennies

    Hi, An old GRE problem asks what the moment of inertia of seven pennies, arranged in a hexagon with one in the center, all touching each others' edges is, about the axis that passes through the center of the central penny and is normal to the plane of the pennies. Each penny is a uniform...
  5. B

    Moment of inertia and axis of symmetry

    Homework Statement Derive an expression for the moment of inertia about the axis of symmetry for a cylinder of mass M , length L and radius a, where the mass density decreases as a function of distance from the axis as 1/r Homework Equations The Attempt at a Solution 1) am i...
  6. S

    How Is the Moment of Inertia Constant Determined Experimentally?

    Homework Statement For a little background, this lab was on energy of a rolling object. We rolled a hollow cylinder from the top of a ramp on a table and onto the floor. We are trying to experimentally derive the constant (k) found in the equation for moment of inertia. Variables: h =...
  7. P

    Rotational Dynamics - moment of inertia finding

    Homework Statement 2 children, masses 35kg and 40kg sit at opposite ends of a 3.4m seesaw with mass 25kg with the fulcrum at midpoint. with the seesaw horizontal find a) the net torque b)angular acceleration Homework Equations tau=rF=Ialpha The Attempt at a Solution i got the right...
  8. D

    Moment of inertia Ixx, Iyy, Izz, Ixy, Ixz, Iyz, etc?

    Help: Moment of inertia Ixx, Iyy, Izz, Ixy, Ixz, Iyz, etc?? Hi all, Can someone help with a few equations?, i need to know the moment of inertia of a section. The section is a column which in the Z direction have 3m, on the X direction has 0.3m and on the Y direction has 0.6m. I know...
  9. P

    Moment of inertia mastering physics

    Homework Statement see attachment Homework Equations The Attempt at a Solution Hey can someone please tell me what I've done wrong here. There is all so a question further down that asks for the same thing but with mass of the bar included.(M_bar)
  10. P

    Moment of inertia and angular speed

    Homework Statement Consider a particle of mass = 19.0 revolving around an axis with angular speed . The perpendicular distance from the particle to the axis is = 0.500 . Homework Equations I=mr^2 K=0.5Iw^2 The Attempt at a Solution I=4.75 K=1796 which is 0.5*4.75*27.5^2...
  11. T

    How to Calculate Moment of Inertia for Different Door Rotations?

    Moment of Inertia - Unsolved Homework Statement A 22 kg solid door is 220 cm tall, 92 cm wide. a) What is the door's moment of inertia for rotation on its hinges? b) What is the door's moment of inertia for rotation about a vertical axis inside the door, 17 cm from one edge? Homework...
  12. P

    How Does Incline Angle and Friction Affect Block and Flywheel Dynamics?

    Homework Statement A block with mass m = 5.00 kg slides down a surface inclined 36.9 to the horizontal. The coefficient of kinetic friction is 0.25. A string attached to the block is wrapped around a flywheel has mass 25.0 kg and moment of inertia 0.500 kgm2 with respect to the axis of...
  13. P

    Inclined plane moment of inertia

    Homework Statement A block with mass m = 5.00 kg slides down a surface inclined 36.9 to the horizontal. The coefficient of kinetic friction is 0.25. A string attached to the block is wrapped around a flywheel has mass 25.0 kg and moment of inertia 0.500 kgm2 with respect to the axis of...
  14. P

    Verification: Hanging mass on cylinder. Moment of inertia

    Homework Statement A 15.0 kg bucket of water is suspended by a very light rope wrapped around a solid cylinder 0.300 m in diameter with a mass of 12.0 kg. The cylinder pivots on a frictionless axle through its centre. The bucket is released from rest at the top of a well and falls 10.0 m to the...
  15. P

    Suspended object moment of inertia

    Homework Statement A 15.0 kg bucket of water is suspended by a very light rope wrapped around a solid cylinder 0.300 m in diameter with a mass of 12.0 kg. The cylinder pivots on a frictionless axle through its centre. The bucket is released from rest at the top of a well and falls 10.0 m to...
  16. P

    Calculating Speed of Block Using Energy Methods | Pulley Moment of Inertia Help

    Homework Statement The pulley in the diagram has a radius of 0.160 m and a moment of inertia 0.480 kg.m². The rope does not slip on the pulley rim. Use energy methods to calculate the speed of the 4.00 kg block just before it strikes the floor Homework Equations The Attempt...
  17. J

    Torque, angular momentum, moment of inertia

    Homework Statement Consider a hollow tube of mass M = 1.2 kg and length L = 1.6 m that rotates about an axle through its center and perpendicular to its length. Inside the tube are two masses, m_1 = 0.4 kg each. These masses are initially held a distance d = 0.8 m apart by a string and...
  18. Q

    Period of a Pendulum and moment of inertia

    Homework Statement A holiday ornament in the shape of a hollow sphere with mass 1.0×10−2 kg and radius 5.0×10−2 m is hung from a tree limb by a small loop of wire attached to the surface of the sphere. If the ornament is displaced a small distance and released, it swings back and forth as a...
  19. P

    Moment of inertia calculation, factor of radius out?

    Homework Statement Ok i have the following problem. There is a pulley with radius 7.5 cm and 2 forces acting on it (2 tensions of a string) acting in opposite directions either side. One is 18.2N, the other 7.5N. I know the acceleration is 3.75 meteres per second squared. Find the moment...
  20. D

    What is the moment of inertia for a sphere rotating about a tangent axis?

    Can someone please tell me the moment of inertia for a solid sphere rotating about an axis tangent to its surface?
  21. H

    Moment of inertia of two objects after collision

    Homework Statement I am working on a lab i did. In the lab we tracked the motion of two pucks that collided. One puck collided into another stationary puck of equal mass in an inelastic collision. We used a video capture system to record the velocity of the pucks before and after...
  22. B

    Moment of inertia of a car tire problem

    Homework Statement A side view of a car tire. Model it as having two sidewall of uniform thickness 0.635 cm and a tread wall of uniform thickness 2.50 cm and width 20.0 cm. Assume the rubber has a uniform density equal to 1.10 X 10^3 kg/(m^3). Radius from the center of the tire to the rubber...
  23. M

    Problem: Rotational Kinematics; Moment of Inertia

    Homework Statement A mass (M) is dropped from height (H) onto one end of a stick of mass (M) and of length (L) pivoted around the opposite end. Upon collision the mass adheres to the stick. Respond to the following in terms of M, L, H, and g. a. Find speed of mass just before impact b. Find...
  24. W

    Moment of Inertia for a Filled Sphere

    Hello. I am attempting to derive the equation for the moment of inertia of a filled sphere. I do not how how to do the proper notation by typing, so I have attached a scan of my work(I apologize if opening the attachment is inconvenient) I keep getting the correct order final equation, but my...
  25. M

    Moment of Inertia for three spherical masses

    Homework Statement 2) Three spherical masses are located in a plane at the positions shown in the figure below. A has mass 39.3 kg, B has mass 35.9 kg, and C has mass 17.6 kg. Calculate the moment of inertia (of the three masses) with respect to the z-axis perpendicular to the xy plane...
  26. S

    Moment of Inertia, for Load along Z-Z axis?

    Assuming that I have a C-Channel When the load acts along the X-X axis, we take Iyy for the Bending moment calculations. Similarly, when load acts along the Y-Y axis, we take Ixx. But if i have a load that acts on Z-Z axis, how do I calculate the Moment of Inertia? PLS SEE THE ATTACHMENTS...
  27. Q

    Calculating Moment of Inertia for a Soldered Wire Wheel

    The problem statement A stiff uniform wire of mass M0 and length L0 is cut, bent, and the parts soldered together so that it forms a circular wheel having four identical spokes coming out from the center. None of the wire is wasted, and you can neglect the mass of the solder. What is the moment...
  28. R

    Moment of Inertia for Earth by superposition

    This was a 2 part problem... PART A: calculate moment of inertia of a uniform sphere of mass M and radius R by using the information provided: the moment of inertia of a thin spherical shell at radius R with mass m spinning about its axis is 2/3mR2. I did this by integrating over thin...
  29. I

    Moment of inertia of disc plus point mass at centre

    Homework Statement A uniform disc radius a, mass m there is rotation about an axis (z) tangental to the disc and in the plane of the disc. a point mass m is placed at the centre of the disc. what is the new moment about the axis z also show that the period of oscillations will...
  30. C

    Moment of inertia about z-axis in spherical coordinates

    Homework Statement Use spherical coordinates to find the moment of inertia about the z-axis of a solid of uniform density bounded by the hemisphere \rho=cos\varphi, \pi/4\leq\varphi\leq\pi/2, and the cone \varphi=4. Homework Equations I_{z} = \int\int\int(x^{2}+y^{2})\rho(x, y, z) dV...
  31. Z

    How Do You Calculate the Moment of Inertia for a Sphere Using Shell Integration?

    Homework Statement calculate the moment of inertia of a sphere of mass M and radius R by integrating over thin shells Homework Equations Ishell=(2/3)mR2The Attempt at a Solution this is what i have so far the sphere is decomposed into infinitesimal shells with surface area 4\pir2 the mass of...
  32. E

    Calculating the Moment of Inertia

    Homework Statement The four masses shown in the attachment are connectec by massless, rigid rods. a) find the coordinates of the center of mass. b) find the moment of inertia about a diagonal axis that passes through mass B and D. Homework Equations I=MR^2...I think. The Attempt...
  33. H

    Finding dimensions of a beam using shear, moment, and moment of Inertia

    Homework Statement Homework Equations Moment of Inertia equation: I=(1/12)bh^3 Stress and Strain equations: Sigma= -(M*c)/I Tao = (V*Q)/(I*t) The Attempt at a Solution I know I need to use shear and moment diagrams to find the max moment so I can use the Stress diagram to...
  34. K

    Calculating Moment of Inertia for a Pulley with Attached Mass

    Homework Statement A 1.65 kg mass is attached to a light cord that is wrapped around a pulley of radius 4.65 cm, which turns with negligible friction. The mass falls at a constant acceleration of 2.40 m/s2. Find the moment of inertia of the pulley. Homework Equations I=mr^2 Torque=I*alpha...
  35. Y

    Help with finding Moment of Inertia

    Homework Statement Determine the moment of inertia of a cylinder of radius 0.37 m, height 1.8 m and density (1.11 − 0.555 r + 0.284 r2) kg/m3 about the center. Answer in units of kg · m2. Homework Equations I=Integral[(r^2)dm] I = mr^2 Density = Mass/Volume Volume of a cylinder =...
  36. K

    How Do You Calculate the Moment of Inertia for a Square?

    Homework Statement Consider a 4 kg square which has its mass concentrated along its perimeter, with each side of length 6 m. (a) What is the moment of inertia of the square about an axis perpendicular to the plane of the square at its center of mass? Use the parallel axis theorem and divide...
  37. D

    Moment of Inertia of a uniform rectangular coil

    Homework Statement A uniform rectangular coil of total mass 270 g and dimensions 1m x 5m is oriented perpendicular to a uniform 4.00-T magnetic field (the figure ). A current of 2.90 A is suddenly started in the coil. Homework Equations angular acceleration = torgue / moment of inertia...
  38. M

    Moment of Inertia and Linear/Angular Momentum

    1. Homework Statement . A very thin 1.0 kg disk with diameter 80 cm is mounted horizontally to rotate freely about a central vertical axis. On the edge of the disk, sticking out a little, is a small, essentially mass-less tab, or "catcher." A 1.0 g wad of clay is fired at a speed of 10.0 m/s...
  39. M

    Moment of Inertia of an Ellipsoid

    I seem to be off by a factor of 2 on the answer to this problem but I can't find where I went wrong. The term in front should be 1/5 and not 2/5. Does anybody see the mistake in my work? It is attached in a word document because I can't figure out how to put the equations into this post...
  40. E

    What is wrong with my derivation for the moment of inertia of a sphere?

    Ok, so I thought about a derivation for the moment of inertia, but my answer comes out to (3/5)MR^2 Basically, what I did was I considered the sphere as a sum of infinitesimally thin spherical shells. The moment of inertia for one shell is dI=(r^2)*dm where dm=(M/V)*4*pi*r^2*dr where...
  41. E

    What is wrong with my derivation for the moment of inertia of a sphere?

    Ok, so I thought about a derivation for the moment of inertia, but my answer comes out to (3/5)MR^2 Basically, what I did was I considered the sphere as a sum of infinitesimally thin spherical shells. The moment of inertia for one shell is dI=(r^2)*dm where dm=(M/V)*4*pi*r^2*dr where...
  42. S

    How Do You Calculate the Moment of Inertia for a Rotating Slab?

    Homework Statement A thin rectangular slab, with dimensions 0.580 m by 0.830 m and mass 0.150 kg, is rotated about an axis passing through the slab parallel to the short edge. If the axis is 0.230 m from the short edge, what is the moment of inertia of the slab? Homework Equations...
  43. O

    Moment of Inertia of a Triangular Prism

    Homework Statement A triangular prism of mass M, whose two ends are equilateral triangles parallel to the xy plane with side 2a, is centered on the origin with its axis on the z axis. Find its moment of inertia for rotation about the z axis. Without doing any integrals write down and explain...
  44. A

    Calculating Torque for a Moving Vehicle Wheel: A Solid Disc Approach

    Homework Statement A vehicle wheel has a mass 2.5 kg and diameter 310 mm. The vehicle moves from rest to a linear velocity of 13 kmh -1 in 60 s. Assuming that the wheel can be treated as a solid disc, find the torque applied to the wheelHomework Equations Not so sure on how to add...
  45. L

    Calculating Moment of Inertia and Rotational Kinetic Energy

    Homework Statement Consider a rigid body with an inertia tensor I =[30, 0, 0; 0, 40, 0; 0, 0, 20] N m s^2 and angular velocity w=10j+10k rad/s. Determine the moment of inertia about an axis parallel to w and find the rotational kinetic energy. The attempt at a solution I'm not sure...
  46. M

    Moment of inertia of rug beater

    Homework Statement There are 2 models of rugbeaters. Model A has a 1m long handle and a 40cm edge length square. The handles mass is 1kg and the squares mass is 0.5kg. Model B has a 0.75m long handle and a square that has 30cm edge length. The mass of the handle is 1.5kg and the mass of the...
  47. I

    Area Moment of inertia of a circular wire

    Hlw...I am a new guy here...And I am taking a course of Applied Mechanics in my freshmen year...Here I have come across a term called Area of moment of inertia which I don't really understand that much...And I have been given to prove that I_d = \frac{\pi a^4}{4} ...I was...
  48. Z

    Can Moment of Inertia Be Transferred Between Two Rotating Bodies in Contact?

    Hi Guys, I've written a clutch model for my simulation based off a few papers I've read which basically deal with it as a state machine; that is there are two separate equations to integrate the motion when it is either locked or slipping. I'm interested to find out if this can be dealt with...
  49. K

    Moment of Inertia and Angular Momentum

    Homework Statement This was a TMSCA (Texas Math and Science Competition) from the physics section. A thin meter stick of mass 200g is positioned vertically on a frictionless table. It is released, slips, and falls. Find the speed of its center of mass just before it hits the table.Homework...
  50. U

    How do I find the Moment of Inertia?

    Homework Statement In this experiment a physical pendulum consisting of a rod and two large rubber stoppers (on top of each other) is swung from a point 1 mm from the end point. Calculate the moment of inertia of the pendulum about the point of suspension? Data: m=mass of rod=97.1 g...
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