The center of mass of a pitched baseball or radius 3.87 cm moves at 36.6 m/s. The ball spins about an axis through its center of mass with an angular speed of 112 rad/s. Calculate the ratio of the rotational energy to the translational kinetic energy. Treat the ball as a uniform sphere.

Respuesta :

Explanation:

It is given that,

Radius of baseball, r = 3.87 cm = 0.0387 m

Speed of baseball, v = 36.6 m/s

Angular speed, [tex]\omega=112\ rad/s[/tex]

Translational kinetic energy, [tex]E_T=\dfrac{1}{2}mv^2[/tex]...........(1)

Rotational kinetic energy, [tex]E_R=\dfrac{1}{2}I\omega^2[/tex]........(2)

I = moment of inertia

For a sphere, [tex]I=\dfrac{2}{5}MR^2[/tex]

Equation (2) becomes :

[tex]E_R=\dfrac{1}{5}Mr^2\omega^2[/tex]...........(3)

Dividing equation (1) and (3). We get :

[tex]\dfrac{E_T}{E_R}=\dfrac{5v^2}{2r^2\omega^2}[/tex]

[tex]\dfrac{E_T}{E_R}=\dfrac{5\times (36.6\ m/s)^2}{2(0.0387\ m)^2\times (112\ rad/s)^2}[/tex]

[tex]\dfrac{E_T}{E_R}=\dfrac{713}{4}=178.25[/tex]

Hence, this is the required solution.

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