system
Given the following post, respond as if you're commenting on Reddit:
human
Temperature is the average kinetic energy of a substance's molecules, so does a substance's temperature increase if its translational speed—and thus translational kinetic energy—increases?

For example, when a pitcher throws a baseball, he increases the ball's translational kinetic energy. Neglecting the affects that drag force has on the ball, does the combined affect of the molecules' translation and vibration cause them to become 'hotter?'
gpt
Keep in mind that kinetic energy relies on velocity and velocity is a relative measure -- that is, it can only be measured relative to something else.

Every object on the universe is moving relative to at least one other object in the universe, so by that measure every object has some kinetic energy at all times. How much depends on what you're measuring it against. 

The heat of an object, say, a baseball, is the average of its molecules' energy relative to each other. When you throw the ball that doesn't really change. The ball moves faster relative to the earth, but the molecules' motions relative to each other don't change.

Now, if it goes really fast, the molecules on the surface experience friction with the air molecules, knocking them around in their natural trajectories and creating disarray against their neighboring molecules... to get hear but just on the surface.