Which best explains why objects fall downward when dropped? a) the center of earth exerts a gravitational pull. b) earth's orbit exerts a downward force on the atmosphere. c) most objects are heavier than the air in earth's atmosphere. d) the force between earth's magnetic poles pulls objects downward.

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 independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of