Today we released a major update to our Working Scale app. We added a second, completely independent method to measure mass. Previously, the app determined the unknown's mass by measuring the angle of tilt of the Android device. The new method makes use of the fact that the oscillation period of an object attached to a spring depends on the mass of the object.
By placing an Android device at the end of a meter stick or yard stick partially overhanging off the edge of a table, you can measure the mass of a small object. Working Scale accomplishes this feat by accurately measuring the oscillation period.
Shown in the picture is a Galaxy Nexus phone at the end of a yard stick with two US quarters. The quality of each measurement is reported as 'good', 'fair', or 'poor'. This feedback is helpful in deciding if the measurement should be repeated.