When waves are closely spaced together, how would you describe the pitch that you hear?

The pitch would be high.

the diagram which shows forces as either balanced = same speed or unbalanced = accelerarting

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.