On the other hand, other gases --- called diatomic --- consist of two atoms held by a bond. This bond can be modeled as a spring, and the two atoms and bond together as a harmonic oscillator. Now, a single molecule's kinetic energy can be increased either by increasing its speed, by making it vibrate in simple harmonic motion, or by making it rotate around its center of mass . This difference is understood in physics through the concept of degrees of freedom : each degree of freedom for a molecule or particle corresponds to a possibility of increasing its kinetic energy independently of the kinetic energy in other degrees.
Context: Scientists are performing some tests on two molecules in order to try to discover how to bring dinosaurs back to life. In the first test, they increased molecule Y's speed, but they didn't do anything to molecule X's speed. They then compared the two molecules to see if they could discern anything useful.
Question: Which molecule has less kinetic energy?