1. Learn: To be able to distinguish between the different types of AP Problems (Kinematics) Do: Apply Kinematics concepts to practice AP Kinematic Problems
Agenda:
Warm Up
Notes (Review)
Changing Representations
Linked Multiple Choice
HW – Read Chapter 2

2. Mechanics--Study of motion of objects and related concepts of force and energy.
Kinematics--description of how objects move
Dynamics--deals with forces and why objects move as they do
Translational motion--objects that move without rotating. The kind of motion involved in movingfrom point A to point B without spinning or vibrating.

3. Frames of Reference
Frames of reference--standard for comparison. “With respect to. . .” Any movement of position,distance, or speed is made against a frame of reference. “With respect to the Earth” is most common. For instance, as you sit at your desk you are moving many, many, miles an hour since you are a passenger on planet Earth. You move as she moves, yet you tend to view motion from your frame of reference and feel as though you are sitting still--not hurtling through space!
Cardinal points--N, S, E, and W
Up (+) and Down(-)
Coordinate axes--origin is “zero”. The z-axis can add a third dimension.

4. Distance vs Displacement
Distance--total “ground” covered--consider your route to school--total mileage put on your car/bike/feetsies
Displacement--change in position of object from starting point only-- “as the crow flies” from your house to school.

5. Vectors
Vectors have BOTH magnitude (size) and direction. The “head” of a vector is at the starting point of the motion or force and the “tail” of the vector is at the end of the journey. Here a person walks 70 m E, then 30 m W, so total distance equals 100 m while the displacement is 40 m to the west.

6. Scalar
SCALAR quantities do not have direction. For instance speed is scalar while velocity is a vector.

7. Average Velocity
You can no longer use the words speed and velocity casually. They have very specific meanings.
Speed--how far an object travels in a given time; how fast it is moving. It is a scalar quantity.
Velocity--Speed with direction attached . a vector.

8. Instantaneous Velocity
Instantaneous velocity--The average velocity over an infinitesimally short time interval.

9. Acceleration
Acceleration--the rate of change of a velocity. A change of velocity with time, if you prefer. If an object’s velocity is changing, it’s accelerating. Yep, even if it’s slowing down!
CAREFUL of the signs. At first you might think accelerating is + and speeding up while decelerating is - and slowing down--NOT SO.
You only have negative acceleration when the direction of the acceleration is opposite to the velocity. It’s all about direction--not speed up, slow down! This is also a vector quantity since it has direction.

10. NOTE THAT ACCELERATION TELLS US HOW FAST THE VELOCITY CHANGES, WHEREAS VELOCITY TELLS US HOW FAST THE POSITION CHANGES.

11. Uniformly accelerated motion--acceleration is constant and motion is in a straight line. DON’T ATTEMPT TO USE ANY OF THESE EQUATIONS UNLESS ACCELERATION IS CONSTANT!

12. The most famous constant acceleration is that due to gravity
The most famous constant acceleration is that due to gravity. Memorize its
value a = g = 9.8 m/s2

13. What falls faster, a rock or a feather?
Neither, in a vacuum that is! Your experience is that the feather would fall more slowly. That’s entirely due to air resistance.

14. Substitute y and yo for x and xo--this is consistent with graphing applications.

15. TWO COMMON MISCONCEPTIONS
Explain the error in these 2 common misconceptions:
1) the acceleration and velocity are always in the same direction
2) that an object thrown upward has zero acceleration at the highest point

16. 3 Final Points of Interest
The speed of a falling object in air or any other fluid does NOT increase indefinitely. If the object falls far enough, it will reach a maximum velocity called the terminal velocity.
Acceleration due to gravity is a vector (as is any acceleration) and its direction, is downward, toward the center of the Earth.
The acceleration of rockets and fast airplanes is often expressed in g’s. Three g’s is equal to
3 x 9.8m/s2 = 29.4 m/s2.