What causes exhalation? a signal from the medulla to the mouth and nose
a signal from the alveoli to the medulla
a signal from the diaphragm to the medulla
a signal from the medulla to the lungs

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?