Calculate Moment of Inertia - Stick and Ball

In summary, the moment of inertia about the y-axis for the given system can be found using standard formulas for the moment of inertia of a stick and a sphere and the parallel axis theorem. No need for integration. It is unclear from the conversation if the task is to practice integration or simply find the moment of inertia for the given bodies.
  • #1
vm310
13
0

Homework Statement


What is the moment of inertia about the y-axis for the system as shown. The stick has a length of 2L and a mass of M. The solid sphere has a diameter of L and a mass of 2M.

4139767990_fd5711c609_o.jpg



Homework Equations



I=[tex]\int[/tex]r2dm
[tex]\lambda=\frac{m}{l}[/tex]


The Attempt at a Solution


Should I have to integrals for this one? one for the stick and one for the sphere? Please help.
 
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  • #2
No need to do any integration, just use standard formulas for the moment of inertia of a stick and a sphere. Hint: Parallel axis theorem.
 
  • #3
vm310 said:

Homework Statement


What is the moment of inertia about the y-axis for the system as shown. The stick has a length of 2L and a mass of M. The solid sphere has a diameter of L and a mass of 2M.

4139767990_fd5711c609_o.jpg



Homework Equations



I=[tex]\int[/tex]r2dm
[tex]\lambda=\frac{m}{l}[/tex]


The Attempt at a Solution


Should I have to integrals for this one? one for the stick and one for the sphere? Please help.

What does your teacher want? Do they want you to solve this using integration? This would take a bit of time for these two bodies. Or have you already been given the moment of inertia of a rod and a sphere and all you really need is the parallel axis theorem?

I guess what I am asking is this an assignment meant for practicing integration using the ideas of linear density and such, or just merely to find the moment of inertia for these bodies?

Doc Al and I must be in some sort of resonance. Sorry again.
 
Last edited:

1. What is moment of inertia?

Moment of inertia is a measure of an object's resistance to rotational motion. It is determined by the object's mass, shape, and distribution of mass.

2. How is moment of inertia calculated for a stick and ball?

The moment of inertia for a stick and ball can be calculated by using the formula I = mr², where I is the moment of inertia, m is the mass of the object, and r is the distance from the axis of rotation to the object's mass.

3. Why is moment of inertia important?

Moment of inertia is important in physics and engineering because it helps determine how an object will respond to rotational forces. It is also used in the design of structures and machines to ensure stability and efficiency.

4. How does the shape of an object affect its moment of inertia?

The shape of an object can greatly affect its moment of inertia. Objects with a larger mass and mass distributed farther from the axis of rotation will have a larger moment of inertia, while objects with a smaller mass and mass closer to the axis of rotation will have a smaller moment of inertia.

5. What units are used to measure moment of inertia?

Moment of inertia is typically measured in units of kilogram-meter squared (kg•m²) in the SI system. However, it can also be measured in units of gram-centimeter squared (g•cm²) or other equivalent units depending on the system of measurement being used.

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