1. T

    Help with moment of inertia questions please

    I would like some help with these two questions about moment of inertia please. -First question: -Second question: For the first question, I have no idea what should I do to start the...
  2. A

    moment of inertia problem

    For the system shown in the figure below, m1 = 7.0 kg, m2 = 2.0 kg, θ = 31°, and the radius and mass of the pulley are 0.10 m and 0.10 kg, respectively. (a) What is the acceleration of the masses? (Neglect friction and the string's mass.) Known Formulas: Torque=...
  3. T

    Inertial "moment" of a solid given an inertia tensor

    Hi all, I am programming some software computing inertial forces of some moving structure. So far, the structure have been represented as a cloud of mass points. For each mass point, inertial forces are computed using some formulas like in this article...
  4. A

    Rotational Power = torque (τ)*(ω) angular velocity? - Problem with units

    I set up an experiment with a pendulum (uniform beam) swinging on a hinge and the hinge attached to a small PMDC generator. The generator had no load attached and its output voltage is proportional to its speed of rotation. I swung the pendulum from 90 degrees and using a data logger I...
  5. F

    inertia formula for con rod

    I am trying to calculate all the forces (in bf) that the connecting rod adds to the engine which influences vibration. I am dividing the rod in between the two ends into four sections and calculating for the middle point of each as if that point had all that sections weight. I am calculating...
  6. J

    Calculate earths mass and moment of inertia

    Hi again everyone, I have a problem (in two parts) where I believe I am tackling the solution with the correct methodology but somewhere along the line I must be going wrong because cannot match my answers to the ones in the book, in fact I am way out (by a factor of 10 to the power 11 or 12...
  7. J

    Moment of inertia generic calculation

    Hi everybody, I am afraid I have come across another Moment of Inertia problem where I cannot see how to proceed to find the solution. It basically gives a cylinder, with generic length, radius and mass of values L, R and M and the fact that density of the cylinder varies linearly with the...
  8. J

    Moment of inertia of a compound body problem

    Hi everyone, I wonder if anyone can help me with a problem which has had me stuck for some time. The problem is as follows - PROBLEM A thin, flat, uniform disk has mass 'M' and radius 'R'. A circular hole of radius 'R/4' centred at the point 'R/2' from the disk's centre is then punched...
  9. K

    D'Alembert and moment inertia of wheel

    Yet another D'Alembert problem. This time a wheel (pulley?) with only one mass but this time I have to account for the moment of inertia. When I tried to frame it mathematically I wrote it down as (F_{applied}-F_{inertial}) \delta s = 0 I ended up with the following. F_{applied} = mg...
  10. J

    Moment of inertia of a human body

    Hi everyone, I have come across a problem and I just don't know how to start to tackle it. The problem is as follows :- Estimate your own moment of inertia about a vertical axis through the centre of the top of your head when you are standing up straight with your arms outstretched. Make...
  11. J

    Moment of inertia for a slender rod of varying mass

    Hi, I have come across a problem where I eventually got the answers to two parts of the problem, but only after I had attempted each part first and got it wrong then, for each part sort of 'reverse-engineered' the solution from knowing what the correct solution was and although I came away with...
  12. J

    Moment of inertia of a compound body

    Good morning all, I am having trouble with a problem to calculate the Moment of Inertia of a body made up of two distinct but linked extended bodies. I have used the generic equations for these two bodies and then added the values to obtain what I thought was the solution but my answer does not...
  13. J

    Moment of Inertia Problem

    Hi, I have come across a problem dealing with calculation of the Moment of Inertia of an extended body and I just don't understand why the answer is what it is. I understand the basic concept of Moment of Inertia in general, and am aware of how you calculate this concept for a variety of...
  14. S

    moments of inertia

    There are two questions about the moments of inertia, but I am lack of the knowledge of calculus. Could anybody help me please? :( 1. Determine the moments of inertia of the shaded area shown with respect to the x and y axes. 2. Determine the polar moments of inertia and the...
  15. T

    Dimensions of Inertia

    Hi All, I asked this once before but there were no answers. What are the dimensions of "Inertia?" Is it a property of matter. Is inertia a vector quantity or a scalar? Is inertia in any of Newton's Laws? I really don't know. Thanks, JP
  16. J

    Help Deriving Moment of Inertia of Solid Sphere (Where did i go wrong?)

    I am attempting to derive the moment of inertia for a solid sphere by summing an infinate amount of thin spherical shells instead of disks. Sphere has radius R Shells have radius r and thickness dr I=sum(mr^2) = integral(r^2dm). to sub out dm in terms of dr, p=m/v so pdv=dm. dv of a shell...
  17. L

    determine the moment of inertia of the x axis of the cross sectional area.

    the ans that i gt is 173.9 , but the ans given is 173.9, which part of my working is wrong?
  18. L

    determine the moments of inertia about the horizontal and vertical axis

    determine the moments of inertia about the horizontal axis and vertical axis for the area. i have my x bar = (100x 10)(50) +(12x80)(6) / (1000+960) =28.4 y bar = (100x 10)(100+5) +(12x80)(20+40) / (1000+960) = 83.0 , then i have attcahed my working for Ixx and Iyy below. The ans given for...
  19. B

    Difficulty with Center of Mass and Moments of Inertia

    Hi there, I really need help on this homework problem to make sure I'm doing it right. It should be in the following picture: I was able to solve Part 1 fairly fast, but Part II has drawn a blank for me overall. I was thinking of that rotational thing from Calculus where you spin a 2D figure...
  20. M

    Moment of Inertia Problem

    This is a problem in my textbook could someone please help me work through it. I don't want the answer I need a clear path to the answer. Here is the question: The moment of inertia of this textbook (a physics textbook) would be the least, about which symmetry axis through its center? Explain...