A molecule has a rotational inertis of 14,000 u.pm^2 and
isspinning at an angular speed of 4.3 X 10^12 rad/s.
a.) Express the rotational inertia in kg.m^2.
b.) Calculate the rotational kinetic energy
inelectron-volts.

Respuesta :

Answer:

(a) [tex]I=2.33\times 10^{-47}\ kg-m^2[/tex]      

(b) [tex]K=1.3\times 10^{-3}\ eV[/tex]

Explanation:

It is given that,

The rotational inertia of a molecule, [tex]I=14000\ upm^2[/tex]

Angular velocity of the molecule, [tex]\omega=4.3\times 10^{12}\ rad/s[/tex]

(a) The molecular weight of a molecule is measured in amu or u.

[tex]1\ amu=1.67\times 10^{-27}\ kg[/tex]

[tex]1 pm=10^{-12}\ m[/tex]

The rotational inertia of the molecule,

[tex]I=14000\times 1.67\times 10^{-27}\times (10^{-12})^2[/tex]

[tex]I=2.33\times 10^{-47}\ kg-m^2[/tex]      

(b) The rotational kinetic energy of the molecule is given by :

[tex]K=\dfrac{1}{2}I\omega^2[/tex]

[tex]K=\dfrac{1}{2}\times 2.33\times 10^{-47}\times (4.3\times 10^{12})^2[/tex]    

[tex]K=2.15\times 10^{-22}\ J[/tex]

Since, [tex]1\ eV=1.6\times 10^{-19}\ J[/tex]

So, [tex]K=1.3\times 10^{-3}\ eV[/tex]

Hence, this is the required solution.