
Read Chapter 1, Section 1.1
Now we will examine the acceleration, velocity and position of a simple system[Drop ball]
Acceleration ? = g = 9.8 m/s^{2} = constant
Velocity:
initial velocity = 0speeds up
follows straight line toward Earth
Results:
 velocity keeps increasing with time
 would move even faster if I threw it down
Mathematically: velocity = initial velocity + acceleration x time
Note: velocity does NOT depend on mass
[Drop balls from different heights]Will the higher one ever catch up with the lower one ?
"catch up" = be at the same height at the same time[Drop from same height  different times]
Will the early one ever catch up with the late one ?
[Drop from same height  different times  different initial velocity]
Will later one catch up now ? maybe
From these experiments and our observations:
position (height) at some time depends on:
 initial position
 initial velocity
 acceleration (often constant)
 time