PASCO ME-9341 INTRODUCTORY ROTATIONAL APPARATUS - Manual (Page 22)

18
Introductory Rotational Apparatus 012-03051F
Name: Date: Group:
➃ Now raise the mass to a starting height of approximately 1 meter. Measure this height care-
fully and record it as h
1
. Release the mass so it falls, reaches it lowest point, then rises again.
Measure and record, h
2
, the greatest height that the mass hanger rises to in its ascent.
➄ Repeat your measurement three times, starting from the same h
1
, and recording the value of h
2
.
➅ Repeat steps 3-5, changing the mass on the hanger, first to 150 grams, then to 200 grams. If
instructed, try the same mass with another pulley. If instructed, repeat the measurements with
two platters. In each case, record the same five values in Table 4.1.
Analysis
Average the final heights, h
2
, for each set of three trials that were performed under identical
conditions. For each trial, determine the amount of gravitational potential energy lost ( GPE)
by the mass in falling from h
1
to h
2
avg: GPE = mg(h
2
– h
1
).
Determine the total distance that the mass moved, d = [(h
1
– h
0
) + (h
2
– h
o
)] = h
1
+ h
2
– 2h
o
.
From this value, and the radius of the step pulley spindle, determine the angular distance, in
radians, that the platter moved:
θ
= d/r.
Now calculate the magnitude of the frictional torque,
τ
f
, using the relationship
τ
f
θ
= GPE.
Compare your results for
τ
f
under the different experimental conditions that you tried.
Report
Your report should include Purpose, Procedure, Data, and Discussion. Include your Analysis
in the Discussion.
Trial r m h
o
h
1
h
2
h
2
h
2
Table 4.1 Data Table 4.2 Calculations
Trial h
2
(avg) GPE d
θ τ
f