# Moment of Inertia confusion

1. Oct 27, 2013

### K.QMUL

1. The problem statement, all variables and given/known data

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.

2. Relevant equations

I = Mr2

What im having difficulty with

I dont understand where this axis is, it would help if someone would explain or better draw a diagram to help me understand.

2. Oct 27, 2013

### Staff: Mentor

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.

3. Oct 29, 2013

### arildno

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?

4. Oct 29, 2013

### K.QMUL

Sorry, i figured it out before everyones reply, so im all good. Thanks for the help though