What Is the Moment of Inertia About a Point One-Fourth the Length from One End?

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Homework Help Overview

The problem involves calculating the moment of inertia of a system consisting of small blocks attached to a rod. The axis of rotation is specified to be perpendicular to the rod and located one-fourth of the length from one end of the rod.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the location of the axis of rotation and its implications for calculating the moment of inertia. There are suggestions to visualize the problem through diagrams to aid understanding.

Discussion Status

The discussion includes attempts to clarify the axis location and its significance. One participant indicates they resolved their confusion independently before receiving further replies, suggesting some productive direction was achieved.

Contextual Notes

There is a mention of the need for a diagram to better understand the axis placement, indicating that visual representation may be crucial for grasping the problem setup.

K.QMUL
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Homework Statement



Small blocks, each with mass m, are clamped at the ends and at the center of a rod of length L and negligible mass

Compute the moment of inertia of the system about an axis perpendicular to the rod and passing through a point one-fourth of the length from one end.

Homework Equations



I = Mr2

What I am having difficulty with

I don't understand where this axis is, it would help if someone would explain or better draw a diagram to help me understand.
 
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K.QMUL said:
I don't understand where this axis is, it would help if someone would explain or better draw a diagram to help me understand.
Did you try drawing a diagram for yourself? The directions seem pretty straightforward.

Draw a line representing the rod. Now draw a line perpendicular to it. If it that perpendicular line were in the middle of the rod, it would be 1/2 the length from one end. Move it so that it's 1/4 the length from one end.
 
Do you agree that one-fourth of the rod length, as measured from one end, must be midway between that end and the center point?
 
Sorry, i figured it out before everyones reply, so I am all good. Thanks for the help though
 

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