What should I know?

1. Objects that change their position by different amounts each second must have changing motion.
2. Motion can change in one of three ways: speeding up, slowing down, or turning. All of these are types of acceleration.
3. By comparing an object's velocities at the beginning and end of a time period, we can measure the average amount of acceleration it experiences.
4. Since acceleration is a comparison of two velocities (m/s) in a unit of time (s), the units for acceleration are meters/second/second.
5. The units for acceleration are often simplified to m/s^2.
6. The acceleration an object experiences must be caused by an unbalanced external force. This type of force is called a net force.
7. Forces always have four characteristics: a cause, an object, a direction and a size, which we abbreviate CODS.
8. In this class, forces are always measured in Newtons, which is a simplified form of the kg * m/s/s.
9. If a force appears not to have a cause, it must not be a true force. An example of this is a centrifugal force.
10. Forces come in two types: contact forces and field forces.
11. Contact forces are pushes or pulls that are applied through a touch.
12. Field forces are pushes or pulls that act at a distance. Gravitational, electrostatic and magnetic forces are all field forces.
13. An analysis of the forces acting on an object can be accomplished using a free body diagram, on which all forces are represented as vector arrows drawn in the correct direction and to the correct relative size.
14. Determination of the size and direction of a net force acting on an object can be made by adding the force vectors on a free body diagram.
15. The acceleration an object experiences is directly proportional to the net force causing it.
16. The acceleration that is produced by a net force must be in the same direction as that net force.
17. A given net force acting on objects of different masses produces different accelerations. The acceleration an object experiences is inversely proportional to the mass of the object.
18. NEWTON'S SECOND LAW OF MOTION summarizes points 12 and 13 in the following formula: F = ma.
19. To use Newtons as the unit of measure of force, mass must be measured in kilograms and acceleration in meters/second/second.
20. Weight is another name for the force of gravity between an object and the Earth.
21. Mass and weight are very different concepts, but related through Newton's Second Law of Motion.
22. Converting a mass (in kg) to a weight (in N) can be done by multiplying the mass by a constant 9.81 m/s/s.
23. The constant in point 21 is the gravitational acceleration -- g -- which represents the acceleration experienced by all objects that fall freely near the Earth's surface.
24. Contrary to popular belief, the mass of an object that falls freely does not affect the acceleration it experiences -- every object that is falling freely experiences an acceleration of g, regardless of its mass.