1. (75%) Practice force and energy problems by completing WeBWorK set
# 5.
2. (25%) In the software download area of the Physics 121
website, located at
http://teacher.pas.rochester.edu/phy121/Software/SoftwareIndex.htm,
you will find a movie that shows elastic and inelastic
two-dimensional collisions. Use LoggerPro to analyze these movies and study the
motion of the center of mass of the two-puck system.
Use the following steps in this analysis:
a. Download
the movie clip from the Physics 121 website.
b. Start LoggerPro.
c. From the
“Insert” menu, select “Movie” to open the movie
you want to analyze.
d. At the bottom
right-hand side of the video window you see a button with red dots
with allows you to “Enable/Disable Video Analysis”. Enable
video analysis a set of tools will appear on the right-hand side of
the video window.
e. Select the
ruler button to set the scale. Use the rulers on the left-hand side
of the video to calibrate your screen. After selecting the ruler button
you move your mouse to one end of the “ruler” in the video,
click-and-hold your mouse button, move your mouse to the other end of
the “ruler,” and release the mouse button. A window
will emerge, asking you for the length the
“green line” you just drew on the screen.
f. Use
the “red-green dot button” to add a “point series” and
use the mouse to the position of one of the two pucks in your collision
video. Each time you select a position in a frame, the video
will advance to the next frame.
g. At the end
of the video, rewind it, use the “red-green dot button” to
add another “point series”, specifying the position of
the other puck.
h. After completing
your data entry you will see that the x and y positions
and velocities for all frames and for both data series are listed in
the data table. These data can be exported by selecting “Export
as …. Text”
from the file menu. The file created can be opened with Excel
and you can use Excel to determine the position of the center of mass
of the system as function of time.
Hand in the two graphs showing the x and y position of the center of mass as function of time
for the elastic and the inelastic collisions and for each movie determine
the average speed of the center of mass. The solution to this
problem needs to be dropped off in the Physics 121 homework locker
in B&L, across from B&L 106. Please make sure your work
is clearly labeled with your name.
Last updated on
Friday, February 29, 2008 9:01
