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Gauranga

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- Thread starter Gauranga
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In summary, an engineer is trying to find the moment of inertia of a part of a machine which looks like the part of a torus as the arc of a circle. He is not familiar with the basic equations for calculating the moment of inertia, so he asks for help from the PF. He provides a link to Wikipedia for more information. He says that he will calculate the moment of inertia by the formula of a hollow torus and then divide it to 8 as the angle between the two radius connecting the arc is 45 degree. He asks for help relating torque and I.omega.2pi/60.

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Gauranga

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- #2

berkeman

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Gauranga said:

Welcome to the PF.

What is the context of the question? Where is this part used, and why do you need its moment of inertia?

What is your math and engineering background? Are you familiar with the basic equations for calculating the moment of inertia?

http://en.wikipedia.org/wiki/Moment_of_inertia

.

- #3

Gauranga

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- #4

W R-P

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- #5

berkeman

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Gauranga said:

Often for hollow things, you can subtract out the quantity for the inner hollow part from the overall solid part. If you can calculate the MofI for a solid torus, you can calculate it for a hollow one...

- #6

gsal

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if you do not find a formula, you may need to go back to the basics and calculate the moment of inertia yourself...

Last edited by a moderator:

- #7

Pyrrhus

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- #8

Gauranga

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- #9

Gauranga

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- #10

Gauranga

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xandro101

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Torque is I* angular acceleration.

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Gauranga

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xandro101

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Yes, u have to get time of acceleration to that speed. Also, is the acceleration uniform?

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Gauranga

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- #15

gsal

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- #16

Gauranga

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- #17

xandro101

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- #18

Gauranga

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- #19

Gauranga

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gsal said:

I am all into it and it is the part of my last question which is proceeding further and further as i have lots to do about it.However thank.

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xandro101

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Yea. I understand now. Thanks.

- #21

Gauranga

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First of all i found the moment of inertia.Then i have the value of a stroke, from where i calculated the rpm.

Then by the formula 2.pi.rpm/60 ,i got the angular acceleration in rad/sec.So i devided the acceleration time by it and got the angular acceleration in rad/sec^2 .

I multiplied that with moment of inertia which was in kg m^2 and got a value in kg.m^2rad/ sec^2.

Where i think rad has no play.so the resulting unit will be Nm which is the right unit for torque.

Can somebody just have a look on the method and say me if i am right?

- #22

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Gauranga said:

Gauranga said:

Looks good. And you're correct about the units, as "rad" is considered unitless.Gauranga said:

First of all i found the moment of inertia.Then i have the value of a stroke, from where i calculated the rpm.

Then by the formula 2.pi.rpm/60 ,i got the angular acceleration in rad/sec.So i devided the acceleration time by it and got the angular acceleration in rad/sec^2 .

I multiplied that with moment of inertia which was in kg m^2 and got a value in kg.m^2rad/ sec^2.

Where i think rad has no play.so the resulting unit will be Nm which is the right unit for torque.

Can somebody just have a look on the method and say me if i am right?

- #23

Gauranga

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Thanks...

The moment of inertia for a machine is a measure of its resistance to changes in rotational velocity. It takes into account the mass of the machine and how that mass is distributed around its axis of rotation.

The moment of inertia is calculated by multiplying the mass of each individual component of the machine by its distance from the axis of rotation, squared. These individual moments of inertia are then summed together to get the total moment of inertia for the machine.

The moment of inertia is important for machines because it affects their ability to resist changes in rotational motion. A larger moment of inertia means that more force is needed to change the rotational speed of the machine, making it more stable and efficient.

The shape of a machine can greatly affect its moment of inertia. Objects with a larger radius of rotation will have a greater moment of inertia, while objects with a smaller radius of rotation will have a smaller moment of inertia. Additionally, the distribution of mass within the machine can also impact its moment of inertia.

Yes, the moment of inertia for a machine can be changed by altering its mass and/or the distribution of that mass. For example, if a machine is made more compact by moving its mass closer to the axis of rotation, its moment of inertia will decrease.

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