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*Question:* A rod of mass and length
pivots
about an axis, perpendicular to its length, which passes through one of its ends. What
is the moment of inertia of the rod? Given that the rod's instantaneous angular velocity is
, what is its rotational kinetic energy?
*Answer:* The moment of inertia of a rod of mass and length about
an axis, perpendicular to its length, which passes through its midpoint is
. This is a standard result.
Using the parallel axis theorem, the moment of inertia
about a parallel axis passing through one of the ends of the rod
is

so

The instantaneous angular velocity of the rod is

Hence, the rod's rotational kinetic energy is written

** Next:** Worked example 8.4: Weight
** Up:** Rotational motion
** Previous:** Worked example 8.2: Accelerating
Richard Fitzpatrick
2006-02-02