PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 19)

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012-03051F Introductory Rotational Apparatus
Experiment 3: Gravitational - Rotational Energy
EQUIPMENT NEEDED:
- Introductory Rotational Apparatus - mass hanger and mass set
- Smart Pulley with table clamp and software, - second pulley with rod
- meter stick - thread
- Apple II or IBM PC or compatible computer
Introduction
In this experiment, you will use a falling mass to apply a constant torque to a rotating
platter. As the mass falls, it loses gravitational potential energy. This lost energy is gained
by the platter as rotational kinetic energy. By measuring the energy lost by the mass and
the energy gained by the platter, you will be able to determine if energy is conserved.
Procedure
➀ Set up the apparatus as shown in
Figure 3.1, with the step pulley
facing up. Use the bubble level to
level the apparatus.
➁ Insert the Smart Pulley software
disk into your computer disk drive
and start up the computer.
[Note: See Smart Pulley manual.]
➂ Measure r, the radius of the
smallest spindle, and record the
value in Table 3.1. Attach a 1.5-meter piece of thread to the step
pulley and wind it up on the smallest of the three spindles. Attach
the mass hanger to the thread, high enough on the thread so the
masses will not hit the floor at the lowest part of their fall. Add
masses to the holder, so the total mass is approximately 50 grams.
Record the total mass as m in the data table. Also measure and
record h
1
, the distance of the hanging mass from the floor.
➃ Hold the Smart Pulley lightly against the edge of the platter. Select
MOTION TIMER from the main menu. Allow the mass to fall
while the Smart Pulley monitors the motion of the platter. Allow the
mass to reach its maximum drop and begin its rise, then push TURN> to stop the timing.
➄ When the computer finishes calculating the times, select GRAPH DATA to move to the
graphing program, selecting ROTATIONAL APPARATUS so the computer knows you are
using the Rotational Apparatus, and then VELOCITY VS TIME for a velocity-time graph.
➅ Examining the graph, you should note that there is a point of maximum velocity, corre-
sponding to the point where the gravitational potential energy reached a minimum and the
rotational kinetic energy reached a maximum. Press , then choose DISPLAY
TABLE OF DATA to see a table of the data. Determine the maximum angular velocity of
the platter, given in rad/sec. Record this value as
ω
max
in Table 3.1.
h
2
h
1
Figure 3.1 Equipment Setup