Measuring the acceleration due to gravity g is a part of most introductory physics classes. A standard method to do so is by using a ticker tape timer. However, frictional forces are usually not included in the analysis even though friction leads to an acceleration significantly smaller than g. In this note, we show how to obtain accurate values of both the gravitational acceleration and the friction force by making measurements with different masses. We also propose a way to organize the laboratory procedure to make the multiple measurements needed, to be more collaborative, and to require students to think more carefully about their results. Students are also exposed to the importance of accounting for the variability in measurements.
References
1.
Uri
Haber-Schaim
, Judson B.
Cross
, John H.
Dodge
, and James A.
Walter
, Laboratory Guide PSSC Physics
, 4th ed. (D.C. Heath
, Lexington, MA
, 1964
), pp. 32
–33
.2.
Dennis L.
Hoeppner
, “Apparatus for Teaching Physics: Improved regularity ticker tape timers
,” Phys. Teach.
7
, 60
(Jan.
1969
).3.
Gerald
Holton
, F. James
Rutherford
, and Fletcher G.
Watson
, Project Physics Handbook
(Holt, Rinehart and Winston
, New York and Toronto
, 1975
), Unit 1, pp. 25
–26
.4.
J.
Jardine
, in Wonder and Delight: Essays in Science Education in Honour of the Life and Work of Eric Rogers 1902–1990,
edited by B.
Jennison
and J.
Ogborn
(IOP Press
, Bristol and Philadelphia
, 1994
), p. 176
.5.
R.
Melton
, “Inexpensive science teaching equipment
,” Sci. Teach.
38
(6
), 69
–74
(Sept.
1971
).6.
We thank Thomas Flanagan, who found the tape timer frequency was (40.05 ± 0.13) Hz using a power spectrum analysis of the audio signal.
© 2020 American Association of Physics Teachers.
2020
American Association of Physics Teachers
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