Use equation I=∫r2dm to calculate the moment of inertia of a slender, uniform rod with mass M and length L about an axis at one end, perpendicular to the rod. Express your answer in terms of the variables M and L.

Respuesta :

Answer:

The moment of inertia is    [tex]I= \frac{1}{3} ML^2[/tex]

Explanation:

From the question we a given an equation

                        [tex]I = \int\limits{r^2} \, dm[/tex]

Now let look at a small length da of this uniform rod that a meters form the x-axis

 The mass of this small section can be mathematically evaluated as

                       [tex]dM = da *\frac{M}{L}[/tex]

For this small portion for the rod the moment of inertia is

                   [tex]dI = (dM)a^2[/tex]

Substituting for dM

                  [tex]dI = da [\frac{M}{L} ] a^2[/tex]

to get I we integrate both sides

                 [tex]I = \int\limits^L_0 {\frac{M}{L} * a^2} \, da[/tex]

                   [tex]= [\frac{M}{L} ][\frac{a^3}{3} ]\left L} \atop {0}} \right.[/tex]

                   [tex]I= \frac{1}{3} ML^2[/tex]