1. Reference Point
2. An object can speed up, slow down, or change direction.
3. Velocity is speed in a direction. Both are distance travelled in a given time but velocity is a vector quantity and you must describe direction.
4. Because the Earth is surrounded by an atmosphere, shape and size of an object will affect the rate of free fall. If an object is shaped to "catch more air" it will fall more slowly than an object that is aerodynamic. In an air-free environment like on the Moon, all objects fall at the same rate. On Earth, objects of similar shape should fall at the same rate too. So the marbles we dropped in class fell at the same rate even though they had different weights.
5. Air resistance or air friction.
6. Law of Conservation of Energy
7. It has reached terminal velocity.
8. Gravity is pulling on each bullet equally. The forward movement of the shot bullet is separate from the downward force of gravity.
9. Energy
10. Chemical potential energy.
11. Kinetic
12. 50 miles/hour
13. 5 meter/second 2
14. Displacement
15. As mass of an object increases, the gravitational pull of the object increases.
16. As density increases, gravitational pull increases (black hole).
