This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

1.
P.
Vogt
and
J.
Kuhn
, “
Analyzing free fall with a smartphone acceleration sensor
,”
Phys. Teach.
50
,
182
183
(
March 2012
).
2.
P.
Vogt
and
J.
Kuhn
, “
Analyzing simple pendulum phenomena with a smartphone acceleration sensor
,”
Phys. Teach.
50
,
439
440
(
Oct. 2012
).
3.
J.
Kuhn
and
P.
Vogt
, “
Analyzing spring pendulum phenomena with a smartphone acceleration sensor
Phys. Teach.
50
,
504
505
(
Nov. 2012
).
6.

In order to obtain a very precise specification of the distance to the rotation center, information on the location of the acceleration sensors within the smartphone must be obtained from the manufacturer. In the iPod touch (4G) the sensors are located underneath the home button; a description of the location for the iPhone 4G can be found online at www.ifixit.com/tear-down/iphone-4-teardown/3130/2 (temporary web address).

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