When a sphere with a moment of inertia [tex]I[/tex] about its center of gravity and mass [tex]m[/tex] rolls from rest down an inclined plane without slipping, its kinetic energy is calculated as:

A. [tex]\frac{1}{2} I \omega^2[/tex]
B. [tex]\frac{1}{2} m v^2[/tex]
C. [tex]I \omega + m v[/tex]
D. [tex]\frac{1}{2} I \omega^2 + \frac{1}{2} m v^2[/tex]



Answer :

Sure, I'd be happy to help explain this step-by-step.

When a sphere rolls down an inclined plane without slipping, its kinetic energy is a combination of translational kinetic energy and rotational kinetic energy. Let's break it down:

1. Translational Kinetic Energy:
This is the energy due to the motion of the sphere's center of mass. It is given by the formula:
[tex]\[ KE_{\text{trans}} = \frac{1}{2} m v^2 \][/tex]
where [tex]\( m \)[/tex] is the mass of the sphere and [tex]\( v \)[/tex] is the velocity of the center of mass.

2. Rotational Kinetic Energy:
This is the energy due to the rotation of the sphere about its own axis. The formula for rotational kinetic energy is:
[tex]\[ KE_{\text{rot}} = \frac{1}{2} I \omega^2 \][/tex]
where [tex]\( I \)[/tex] is the moment of inertia of the sphere about its center of mass and [tex]\( \omega \)[/tex] is the angular velocity.

Since the sphere rolls without slipping, there is a relationship between the translational velocity [tex]\( v \)[/tex] and the angular velocity [tex]\( \omega \)[/tex]. Specifically, this relationship is given by:
[tex]\[ v = \omega R \][/tex]
where [tex]\( R \)[/tex] is the radius of the sphere.

Combining both types of kinetic energy, the total kinetic energy ([tex]\( KE_{\text{total}} \)[/tex]) of the rolling sphere is:
[tex]\[ KE_{\text{total}} = KE_{\text{trans}} + KE_{\text{rot}} \][/tex]
[tex]\[ KE_{\text{total}} = \frac{1}{2} m v^2 + \frac{1}{2} I \omega^2 \][/tex]

Thus, the kinetic energy when a sphere rolls down an inclined plane without slipping is:
[tex]\[ \frac{1}{2} I \omega^2 + \frac{1}{2} m v^2 \][/tex]

So the correct option is:
D. [tex]\(\frac{1}{2} I \omega^2 + \frac{1}{2} m v^2\)[/tex]