Phys 111L
Fall 2007
Laboratory 7: Rotational Motion
The behavior of physical systems in general can be described in terms of standard
variables such as velocity, acceleration, force, energy and momentum. Although this
scheme is applicable to all classical physical systems, it is useful to used modified versions
of the standard variables when describing orbital or rotational motion.
The goal of this laboratory is to introduce you to variables suitable for describing
the kinematics of rotational motion: angular position, angular velocity and angular
acceleration.
1 Angular Velocity and Angular Acceleration: Theory
Complete sections I and II of the workbook exercise, “Rotational Motion” (this is
an excerpt from “Tutorials in Introductory Physics” by McDermott and Shaffer).
2 Angular Velocity and Angular Acceleration: Experiment.
The laboratory is equipped with a PASCO rotary motion sensor with an attached
rotating arm. The rotary motion sensor can measure angular position and velocity.
There is also a PASCO smart pulley which can be used to measure linear (ordinary)
velocity.
a) Connect the PASCO rotary motion sensor and configure it so that it records angular
position, measured in rad/s, and angular velocity, measured in rad/s2.
b) Configure the display so that it displays graphs of angular position vs. time and
angular velocity vs. time in the same window.
c) You will rotate the arm at approx-
imately constant angular velocity in
four different combinations of fast vs.
slow and counterclockwise vs. clock-
wise. Using a single set of axes, sketch
and label predicted graphs of angu-
lar velocity vs. time for motion:
i) counterclockwise at a slower
rate,
ii) clockwise at a slower rate,
iii) counterclockwise at a faster rate,
and
iv) clockwise at a faster rate.
Time
Angular velocity
