We often take the force of gravity for granted, even though Earth's gravity is what keeps each of us from floating off into space! In this lesson, students begin to more fully understand and appreciate the force of gravity. They predict what will happen when a whole apple and half an apple are dropped at the same time from the same height then test their predictions. Next, they observe cannonballs of different masses being dropped out of a tower, and leaking cups being dropped into a bucket. These activities demonstrate that all objects fall at the same rate, regardless of their mass--a concept known as the law of falling bodies. Students then watch a video segment showing a NASA astronaut dropping a feather and a hammer on the Moon. They repeat the activity in the classroom then consider why these objects fall at the same rate on the Moon but not on Earth. Finally, they use what they have just learned to predict what will happen when two balls of the same mass but different volumes--and then two balls of different masses but the same volume--are dropped at the same time from the same height.
