Moment of Inertia - Need Guidance

The pendulum has a total mass of 6.6 kg and a moment of inertia of 0.89 kg*m^2. The disk has a total mass of 1.7 kg and a moment of inertia of 1.35 kg*m^2. Adding these two values together, the total moment of inertia of the pendulum about the pivot point is 2.24 kg*m^2. In summary, the pendulum has a total mass of 6.6 kg and a moment of inertia of 0.89 kg*m^2, while the disk has a total mass of 1.7 kg and a moment of inertia of 1.35 kg*m^2. The total moment of inertia of
  • #1
hoseA
61
0
A pendulum is made of a rod whose moment
of inertia about its center of mass is
1/12ML^2 where its mass is 4.9 kg and and its length
is 3.3 m, and a thin cylindrical disk, whose
moment of inertia about its center of mass
is 1/2MR^2, where its mass is 1.7 kg and its
radius is 1.6 m.

What is the moment of inertia of the pen-
dulum about the pivot point? Answer in units
of kg*m^2.

I tried adding the moment of Inertias --> ([1/12 (4.9) (3.3)^2 ]+[1/2 (1.7)(1.6)^2] = 6.62275.

This is obviously wrong. I have know clue how to approach this. I think there's a theorem (parallel theorem?) that will help but I don't know how to apply it. Help is much appreciated.
 
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  • #2
The disc is at the END of the rod. Whats the distance of the disk from the pivot point then?
 
  • #3

FAQ: Moment of Inertia - Need Guidance

What is moment of inertia?

Moment of inertia is a measure of an object's resistance to changes in its rotational motion. It is also known as rotational inertia.

How is moment of inertia calculated?

The formula for moment of inertia is I = mr², where I is the moment of inertia, m is the mass of the object, and r is the perpendicular distance from the axis of rotation to the mass.

What is the importance of moment of inertia?

Moment of inertia is important in understanding an object's behavior when it is rotating. It helps determine how much energy is needed to change an object's rotational speed and how stable an object will be while rotating.

How does moment of inertia differ from mass?

Mass is a measure of an object's resistance to linear motion, while moment of inertia is a measure of its resistance to rotational motion. They both play important roles in an object's overall motion.

What factors affect moment of inertia?

The moment of inertia of an object depends on its mass, shape, and the distribution of mass around its axis of rotation. Objects with more mass and mass located further from the axis of rotation will have a higher moment of inertia.

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