contestada

Calculate the rotational inertia of a meter stick, with mass 0.71 kg, about an axis perpendicular to the stick and located at the 18 cm mark. (Treat the stick as a thin rod.)

Respuesta :

To solve this problem we will use the parallel axis theorem for which the inertia of a point of an object can be found through the mathematical relation:

[tex]I = I_{cm} +mx^2[/tex]

Where

[tex]I_{cm}[/tex] = Inertia at center of mass

m = mass

x = Displacement of axis.

Our mass is given as 0.71kg,

m = 0.71kg

Para a Stick with length (L) the Moment of Inertia of the stick about and axis passing through the center and perpendicular to stick is

[tex]I_{cm} = \frac{1}{12} mL^2[/tex]

[tex]I_{cm} = \frac{1}{12} (0.71)(1)^2[/tex]

[tex]I_{cm} = 0.05916Kg\cdot m^2[/tex]

The distance between center of mass to the specific location is  

[tex]x = 50cm - 18cm[/tex]

[tex]x = 38cm = 0.38m[/tex]

So, from parallel axis theorem ,

[tex]I = I_{cm} + mx^2[/tex]

[tex]I =0.05916Kg\cdot m^2+ (0.71kg)(0.38m)^2[/tex]

[tex]I = 0.161684Kg\cdot m^2[/tex]

Therefore the rotational inertia is [tex]0.161684Kg\cdot m^2[/tex]