2) decrease
no ext torque Iw=const
temp inc. mass distribution inc. I inc.
w dec.
am I right?

Introduction:
In order to analyze the effect of rotational speed on the temperature of a solid metal sphere, it is important to consider the principles of rotational motion and the relationship between temperature and kinetic energy.

Principles of Rotational Motion:
When a solid metal sphere rotates about its diameter, it experiences a centripetal force that is directed towards the center of rotation. This force causes the sphere to move in a circular path and creates a tension within the material of the sphere.

Relationship between Temperature and Kinetic Energy:
The temperature of an object is directly related to its average kinetic energy. When the kinetic energy of the particles within the material increases, the temperature also increases.

Effect of Rotational Speed on Temperature:
Based on the principles mentioned above, we can deduce the following regarding the effect of rotational speed on the temperature of the solid metal sphere:

1. Increased Rotational Speed:
When the rotational speed of the sphere increases, the tension within the material also increases. This increased tension leads to an increase in the kinetic energy of the particles within the sphere, resulting in an increase in temperature.

2. Decreased Rotational Speed:
Conversely, if the rotational speed of the sphere decreases, the tension within the material decreases as well. This leads to a decrease in the kinetic energy of the particles within the sphere, causing the temperature to decrease.

3. Constant Rotational Speed:
If the rotational speed of the sphere remains constant, the tension within the material also remains constant. As a result, the kinetic energy of the particles within the sphere does not change, and therefore, the temperature remains constant as well.

4. Increased then Constant Rotational Speed:
If the rotational speed of the sphere initially increases and then becomes constant, the tension within the material initially increases, causing an increase in temperature. However, once the rotational speed becomes constant, the tension also becomes constant, resulting in a stable kinetic energy and temperature.

Conclusion:
In summary, the effect of rotational speed on the temperature of a solid metal sphere depends on whether the rotational speed increases, decreases, remains constant, or initially increases and then becomes constant. Understanding the principles of rotational motion and the relationship between temperature and kinetic energy helps in comprehending these effects.