9. In an experiment, the independent variable is (2 points)
never changed by the scientist
not important to the scientist
not recorded by the scientist
changed by the scientist

1) never changed by scientists

Explanation:

Your independent variables are the things that remain constant and never change. your dependent variable is changes.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

a) electrical > light, sound, and thermal< < < <

) the mechanical energy of the firefighter moving.< < < < a) electrical > light, sound, and thermal< < < <

c) both a and b.