What should I know?

1. The position of an object can only be determined by reference to some other point -- called a reference point.
2. This position is really a distance away from that reference point in a particular direction.
3. In this class, distances are nearly always measured in meters.
4. As in all sciences, observations in the form of measurements must be both as precise and as accurate as possible. Precision is reported as a measurement's number of significant figures, and accuracy is often reported as a percent error.
5. The choice of a reference point is up to the observer. It should be chosen in a way that makes the most sense for the observer or that makes future observations the easiest to analyze.
6. The set of all the positions and motions of objects from a particular reference point is called a frame of reference.
7. Motion is observed when an object's position -- the distance and direction it is from a reference point -- changes in a particular frame of reference.
8. It is possible for an object to move in one frame of reference but not move in another frame of reference.
9. Constant motion in a frame of reference occurs when an object's position changes by the same amount and in the same direction in equal units of time.
10. Objects at rest in a given reference frame are also considered to have constant motion. Being "at rest" means that the object is not moving in that reference frame.
11. In this class, time is nearly always measured in seconds.
12. The distance that an object covers in a second is called that object's speed.
13. The change in the object's position -- both its distance from a reference point and its direction from that reference point -- is called its velocity.
14. Speed and velocity are not synonyms: speed is a scalar measurement -- one that does not require a direction, and velocity is a vector measurement -- one that does require a direction.
15. Unbalanced forces -- pushes or pulls on the object -- are required to change the motion of an object.
16. It is the natural state of objects that are not experiencing any unbalanced forces to move with a constant velocity.
17. Objects will resist changes to their velocity in an amount that is proportional to their mass. This property is known as inertia.
18. The greater the mass of an object, the more difficult it will be change its velocity. This means that it will be harder to slow it down, to speed it up, or to turn it.
19. In this class, mass is nearly always measured in kilograms.
20. The base units of meters, kilograms and seconds make up the foundation for the MKS system of units, which includes nearly all the units we will use in this class.
21. NEWTON'S FIRST LAW OF MOTION -- also called the Law of Inertia -- states that objects resist changes in their velocity until they are acted upon by an unbalanced force.