PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 6)

2
Introductory Rotational Apparatus 012-03051F
The following equipment is included with the ME-9341
Introductory Rotational Apparatus (see Figure 2):
– Base with leveling supports and main bearing
– Spindle
– Main platter with step pulley
– Pulley clamp
– Tensioning screw
– Level
– Photogate clamp
– Steel bar
– Auxiliary platter
– Steel ring
– Instruction manual and experiments guide
You will also need either:
A PASCO Smart Pulley System (Model ME-9420 or
ME-9421) or one of the Smart Pulley Timers (ME-
9382, ME-9384, ME-9386, or ME-9388) - (Please see
the PASCO catalog for complete details.) - and an
Apple II or IBM PC (or compatible) computer.
or
A photogate timing system such as PASCO Model
ME-9206A or ME-9215A.
Measuring Equipment Parameters
In experiments with the Rotational Apparatus, you
will often be comparing experimentally determined
values, such as moment of inertia or angular accelera-
tion, with calculated values based on theory. These
listed, precalculated values may be helpful in those
calculations. For best results, however, we recom-
mend that you make the necessary measurements
yourself. The following suggestions may be helpful
in making certain measurements accurately:
➀ To measure the radii of the step pulley, use calipers
to determine the diameter, then divide by two.
➁ To measure the radius of the Smart Pulley groove,
observe the LED on the top of the photogate as you
pull a string over the pulley. Measure the distance,
L, through which you pull the string for a predeter-
mined number, n, of LED flashes. The radius of
the pulley groove is then r = 3L/2 n for a 3-hole
pulley or r = 10L/2 n for a 10-spoke pulley.
➂ To measure the radius of the Smart Pulley outer cir-
cumference, roll the Smart Pulley over a smooth,
flat surface. Measure the distance, L, over which
you pull the pulley for a predetermined number, n,
of LED flashes. Again, the radius of the outer cir-
cumference of the pulley is r = 3L/2 n for a 3-hole
pulley or r = 10L/2 n for a 10-spoke pulley. (You
can draw a mark on the edge of the rim of the Smart
Pulley to use as a reference mark for measuring L.)
➤NOTE: If you would rather not make the
measurements yourself, use the values in the box
below. They should be valid to within 10
percent for your Rotational Apparatus.
Main platter: Mass = 991 gm; Radius = 12.7 cm;
Moment of inertia = 7.50 x 10 -3
kgm
2
Step pulley: Radii = (1.50 cm, 2.00 cm, 2.50 cm)
Auxiliary platter: Mass = 894 gm; Radius = 12.7
cm; Moment of inertia = 7.22 x 10 -3 kgm 2
Steel bar: Mass = 690 gm; Dimensions = 22.2 x
5.1 cm; Moment of inertia = 2.98 x 10 -3 kgm 2
Steel ring: Mass = 701 gm; Outer radius = 6.4 cm;
Inner radius = 5.4 cm;
Moment of inertia =2.46 x 10
-3
kgm
2
Smart Pulley: 3-hole 10-spoke
radius inside groove 2.29 cm 2.38 cm
radius outside circum. 2.51 cm 2.54 cm
moment of inertia 15.3x10
-7
kgm
2
18.6x10
-7
kgm
2
Note: Platters of the earlier versions of the ME-
9341 were made from masonite. Their mass and
moment of inertia are given below.
Main platter: Mass = 776 gm; Radius = 12.7 cm;
Moment of inertia = 6.01 x 10
-3
kgm
2
Auxiliary platter: Mass = 694 gm; Radius = 12.7
cm; Moment of inertia = 5.82 x 10
-3
kgm
2
Equipment