Is mechanical energy conserved as a playground swing moves? why or why not?

NO

Explanation:

No, because as it swings it is mechanical energy that changes from almost completely potential energy to almost completely kinetic energy and thermal and sound.

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

search it up!

explanation: