A man is sitting on a chair with wheels. He grabs a 2.1 kg book from the desk and throws the book at a speed of 7.2 m/s. His chair moves backward. The man has a mass of 70 kg and
the chair has a mass of 9.2 kg. What is the speed of the man and the chair after the book is
thrown?

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

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.

because if the tool that you are using is not balanced it there would be false mass.