Intellectual health is

activities that stimulate the mind

Intellectual health refers to activities that stimulate the mind and includes many forms of personal expression. Aspects of intellectual health include learning and using life skills such as critical thinking, decision-making, organization, and problem-solving.

Explanation:

frequency or wavelenth of em radiation in a vacuum

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.