3. Tennis ball and rubber band. Because gravity pulls in and the rubber band bounces back as its pulled back in to the tennis ball.
4. A model is useful because the Earth is to big to use so we shrank it as a model and it is way easier then going in space and observing it and taking many pictures and videos.
5. The Earths gravity does effect the moon because each time the Earth spins the moon gets pulled closer and goes farther when the Earth gets pulled to the sun.
6. Birds don't fall because their wings push off gravity when they flap their wings and planes use jets to push off of gravity.
7. Gravity never stops working. You might think so because when you jump you think hey gravity stopped for a few minutes but no, no force can stop gravity.
8. Because craters get pulled to the Earth because of gravity.