Well, if your question is how light affects plants,
then you would want to design an experiment that plays aruond with the amount of light a plant gets
thus the thing changing (or variable) would be amount of light
Answer:
it is atoms and molecules
When a car is slowing down, it has a negative acceleration. Although it is not going a negative speed, it is decreasing in velocity, which is the definition of a negative acceleration.
Hope this helps!
