Rotational inertia Definition and 182 Threads

Homework Statement The rectangle shown has a mass, m. The sides are made of uniform thin wire. The short side is of length a, and the long side is of length b. If m = 5.50 g, a = 0.05 cm and b = 0.1 cm, what is the moment of rotational inertia about the axis indicated? (ignore the x's)...

Does anyone know what the rotational inertia of a cube of uniform density is when it is rotated about an edge? Any help is appreciated!

First questionThree identical balls, with masses M, 2M, and 3M are fastened to a massless rod of length L as shown. The rotational inertia about the left end of the rod is: Thats the layout below. Would calculus be needed in this problem (intergration) because then I am in trouble. I know the...

Hello: I seem to be stuck on this one problem: "A meter stick is suspended vertically at a pivot point 0.26 meters from the top end. It is rotated on the pivot until it is horizontal and then released from rest. What will be its maximum angular velocity (in radians per second)?" So I...

I am having problem with a relatively simple problem that I probably have done before but because my Physics have become so rusty recently I just can't get the right answer. You have a disc that sitting about some point P on the ground - so its upright - and there is a hole cut out on the top...

A yo-yo shaped device mounted on a horizontal frictionless axis is used to lift a 30kg as shown. The outer radius R of the device is 0.50m, and the radius r of the hub is 0.20 m. Wen a constant horizontal force F of magnitude 140N is applied to a rope wrapped around the outside of the device...

A bowler throws a bowling ball of radius R=0.11m along a lane. The ball slides on the lane with initial speed V of center of mass = 8.5 m/s and initial angular speed w = 0. The coefficient of kinetic friction between the ball and the lane is 0.21. The kinetic frictional force f acting on the...

I am probably not taking the AP physics C tests, but I have the book from when I studied by myself for the AP physics B test, and it has all the Physics C stuff in there as well. Now, with that said, there is a section in rotational motion. Most of it makes perfect sense mathematically, but...

A lawn roller in the form of a hollow cylinder of mass M is pulled horizontally with a constant force F applied by a handle attached to the axle. If it rolls without slipping, find the acceleration and the frictional force. Let R1 be the radius of the hollow and R2 the outer radius, and (alpha)...

A thin rectangular sheet of steel is .3m by .4m and has mass 24kg. Find the moment of inertia about an axis (a) through the center, parallel to the long sides; (b) through the center parallel to the short sides. (c) through the center, perpendicular to the plane. (a) We divide the sheet into N...

I need to compare a wheel and tire package on my car and I need help calculating for rotational inertia. I am comparing the weights and size of two different wheels and tires, and so far, this is what I have gathered: 14" wheel & tire (tire is a 195-60-R146): Overal Diameter - 23.2126"...

Let's say that something is spinning and it spins in a certian direction. The object has rotational inertia. Now say that the object has no inertia. How many times will the object change its direction of rotation in under a second?

HI ,I don't get the correct answer the the following problem. A 3kg solid wheel , rolling without slipping on a horizontal surface has a rotational inertia about its given by (MR^2)/2, where M is its mass and R its radius, A force applied to the axle and the center of mass has an...

A cylinder of mass M and radius R smoothly rolls from rest along a ramp and onto a final horizontal section. From there it rolls off the ramp and lands on a floor at a horizontal distance of d = 0.505 m from the end of the ramp. The initial height of the cylinder is H = 0.98 m; the height h of...

A uniform solid disk of radius 4.18 m and mass 193 kg is free to rotate on a frictionless pivot through a point on its rim. The acceleration of gravity is 9.8 m/s2 : If the disk is released from rest in the po- sition shown by the solid circle, what is the speed of its center of mass...

A rotating door is made from four rectangular glass panes, as shown in the drawing. The mass of each pane is 76 kg. A person pushes on the outer edge of one pane with a force of F = 55 N that is directed perpendicular to the pane. a.) Find the rotational inertia of the door. b.) Find the...

Calculate the rotational inertia of a wheel that has a kinetic energy of 20300 J when rotating at 794 rev/min. I don't understand this whole rotational inertia thing too well but I thought I found the right equation, but apparently I didn't. I used K = 1/2 * I * w^2 I converted the 794 rev/min...

Hi, Please take a look at this: Calculate the rotational inertia of a section of a right circular cylinder of radius R that subtends an angle of 'theta knot' at the origin when the reference axis is at the origin and perpendicular to the section. I tried to draw the picture in the...

Hi, I have hard time understanding the rotational inertia . A string is wrapped around a cylindar spool of radius 1cm. The axis of the spool is fixed. A length of string of .8 m is pulled off in 1.5 s at a constant tension of 20N. What is the rotational inertia of the spool? Can I have some...

Let's assume for a moment that we have two objects: a solid cylinder rotating about the center, and a section of a cylinder with a given angle rotating about the center of the would-be cylinder (had it been a full cylinder). They have an equal radii, and we will modify their mass-densities in...

How would I prove that the Rotational Inertia of a unform sphere is 2/5M(R)squared, about any axis?:confused:I have no idea where to start. . .

i know that the equation for rotational inertia of a hoop is different than the equation for a solid cylinder, but what is the equation for a rectangular cube in a hoop? _ \ -> \ (|) <--is what I mean if the diagram helps at all <-

Hello, After a few hours of searching for an active physics message board, I was so happy to find this one and I am hoping for some assistance :smile: I am not looking for homework answers, I have already completed this assignment to the best of my knowledge. I got my paper back today...

I would like to further understand rotational inertia. I understand that for a point mass, I = MR^2 and for a continuous object it is basically the sum of all "little" MR^2 for each element of that object. I get a little fuzzy when actually solving for I for an object. For example, if we have a...

if a ball, a solid cylinder, and a hollow pipe each with equal masses and radius are released simultaneously from an inclined plane, which will reach the bottom first? i would say the pipe would reach the bottom first, because the rotational inertia of the pipe is greater than that of the other...

Hello,mates.i`,ve been struggling to demonstrate the procedure to calculate the rotational inertia of a hollow/empty sphere around an axe that passes through its diameter.Please,could you shed me some light or show me the procedure(Even show me any online papers on it)I`d be Glad.Please help...

Help with this problem... The Rotational inertia of an object depends not on the mass alone but on the distribution of the mass. Between a hoop and a solid sphere of the same mass which object has higher rotational inertia when they are rolled? Explain how the distribution of the mass affects...

Just how do you calculate the rotational inertia of a sphere? Assuming the sphere lies at the center of the xyz coordinate system, I divided the sphere into a series of cross-sections of verticle width dz and area pi*y^2. I then multiplied these together and multiplied this by z^2, and...

Alright, I absolutly do not understand this concept. I missed the lecture and the textbook does not seem to explain it very well. Here is a sample question: Two particles, each with mass m = 1.10 kg, are fastened to each other, and to a rotation axis at O, by two thin rods, each with...

Someone please tell me is I am doing this problem correctly.If I have a thick spherical shell with inner radius r, outer radius R, and mass M, I am getting [(2/5)M/(R^3-r^3)](R^5-r^5). It is not the same thing as subtracting I of large sphere from I of smaller one, different than (2M(R^2-r^2)...

A rod of mass M and length L, initially standing, falls in such a way that the center of mass experiences only vertical motion. What is the moment of inertia of the rod? I picture the rod as having both translational and rotational motion since it's rotating about an axis through the CM which...

Two particles, each with mass m = 5.4 g, are fastened to each other and to a rotation axis at P, by two thin rods, each with length L = 0.68 m and each with a mass of 7.9 g, as shown. The combination rotates around the rotation axis with an angular velocity of 10.4 rad/s. Find the rotational...