Wed Sept 30, 2009, IB Physics 1-1A

HW: RA 2.3
Problem sheet: 17, 18, 19, 20

Asked if there were questions on RA 2.2
Collected RA 2.2

Reviewed results of Picket Fence Lab

Showed how to calculate how fast using definition of acceleration in the form
vf = vi + a*t
which works if the acceleration is constant.

Did several examples of "how fast?" for dropping a ball, throwing a ball down, and throwing a ball up.

Showed how you can modify equation for distance: d = v * t into
displacement = v avg * t
in order to find how far you are and in what direction from your starting point.
If the acceleration is constant, which it is near the surface of the earth, and air resistance can be ignored, then v avg = (vi + vf)/2

Did several examples of finding "how far?"

This is the sus-it-out method which you will use in your rocket lab 1 (hopefully on Friday)

Gave students ~ 25 minutes in class to work on RA 2.3 and on problems from problem set.