An atom with 4 protons, 5 neutrons, and 4 electrons has an atomic mass of amu. (enter a whole number.) numerical answers expected! if anyone has or had mrs. pennington i have a terrible grade on flvs. inbox me too

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the dependent variable in galileo's experiment?