PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 15)

11
012-03051F Introductory Rotational Apparatus
Experiment 2: Angular Acceleration—2
EQUIPMENT NEEDED:
- Introductory Rotational Apparatus with auxiliary platter, ring, steel bar, and bubble level
- Smart Pulley with table clamp and software
- thread
- A second pulley with rod - mass hanger with mass set
- Apple II or IBM PC or compatible computer,
When a force causes an object to rotate, the angular acceleration of the object depends upon
four factors: (1) the magnitude of the force, (2) the direction of the force, (3) the point on the
object at which the force is applied, and (4) the rotational inertia of the object. In this lab you
will investigate the quantitative relationship between these four factors and the angular accel-
eration of a rotating system. A falling mass will be used to apply the force.
Procedure
➀ Set up the apparatus as shown in Figure 2.1.
Then use the bubble level to level the apparatus.
➁ Insert the Smart Pulley Timer software disk into
your computer disk drive and start up the com-
puter.
[Note: See Smart Pulley manual.]
➂ Attach a 2-meter piece of thread to the step
pulley and wind it up on the smallest of the three
spindles. Attach the mass holder to the other end
of the thread by wrapping 4-5 turns around it.
Add masses to a total of 40 grams (remember,
the mass of the hanger is 5 grams).
➃ Hold the Smart Pulley lightly against the edge of
the platter. If the LED is OFF, rotate the platter
slightly until it lights up. Now select MOTION TIMER from the main menu. Release the
mass so it falls while the Smart Pulley monitors the motion of the platter. Just before the mass
hits the floor or the thread runs out, push to stop the timing.
➄ When the computer finishes calculating the times, examine the data table. If you think your
run was good, press , then select GRAPH DATA to move to the graphing pro-
gram. When asked to identify the type of device you used to interrupt the photogate, select
ROTATIONAL APPARATUS. Then select VELOCITY VS TIME for a velocity-time graph.
➅ For the graph style, select STATISTICS, so the computer will do a statistical analysis of your
data (press the S-key, then press the space bar so a check appears to the left of your selection).
When the graph is constructed, there will be three sets of numbers at the top. "M" is the slope
of the graph, which is the angular acceleration of the platter in rad/sec
2 .
➆ In Table 2.1, record the angular acceleration, the mass you used, and the radius of the step
pulley spindle around which the thread was wrapped.
➇ Repeat steps 4-7 with the same mass but the next largest spindle of the step pulley. Then
repeat again using the largest spindle.
➈ Repeat again, using the smallest spindle, but use masses of 80, 120, 160, and 200 grams.
Figure 2.1 Equipment Setup