With the development of digital technology, plentiful sensors are embedded in the smartphone, which makes it a valuable tool for teaching elementary experimental physics. For instance, the magnetic field sensor of the smartphone has been used to measure gravitational acceleration by measuring the magnetic pendulum’s oscillation period. The pressure sensor has helped explore the relationship between atmospheric pressure and altitude. The speed of sound in air can be easily measured using two smartphones with a sound sensor. Recently, Kim et al. put forward a smartphone “multiple tasking” method to analyze free-falling motion and measure the acceleration due to gravity; however, it involved a complex error analysis. To solve the problem, this experiment uses the acoustic stopwatch sensor of the smartphone, which can record the time of free-falling motion accurately.

1.
U.
Pili
,
R.
Violanda
, and
C.
Ceniza
, “
Measurement of g using a magnetic pendulum and a smartphone magnetometer
,”
Phys. Teach.
56
,
258
(
2018
).
2.
Martín
Monteiro
, “
Exploring the atmosphere using smartphones
,”
Phys. Teach.
54
,
308
309
(
2016
).
3.
Sebastian
Staacks
 et al, “
Simple time-of-flight measurement of the speed of sound using smartphones
,”
Phys. Teach.
57
,
112
113
(
2019
).
4.
J.
Kim
 et al, “
A measurement of gravitational acceleration using a metal ball, a ruler, and a smartphone
,”
Phys. Teach.
58
,
192
194
(
2020
).
5.
Ryan
Carroll
and
James
Lincoln
, “
Phyphox app in the physics classroom
,”
Phys. Teach.
58
,
606
607
(
2020
).
6.
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