Note, that there is a possibly confusing distinction between “Acceleration with g” and “Acceleration (without g)”. The sensor in your phone actually measures a force on a sample mass, which includes the contribution from gravitational acceleration. Therefore, this sensor will report the earth’s acceleration of 9.81 m/s² while the phone is resting (which is what we call “Acceleration with g”). In contrast, the physical acceleration is zero when the phone is resting (or moving at a constant speed), so most phones offer a virtual sensor which subtracts the constant acceleration (usually by taking into account the data from other sensors as well). This is what we call “Acceleration (without g)” and it will actually report an acceleration of zero while the phone is not accelerated.

Note, that there is a possibly confusing distinction between “Acceleration with g” and “Acceleration (without g)”. The sensor in your phone actually measures a force on a sample mass, which includes the contribution from gravitational acceleration. Therefore, this sensor will report the earth’s acceleration of 9.81 m/s² while the phone is resting (which is what we call “Acceleration with g”). In contrast, the physical acceleration is zero when the phone is resting (or moving at a constant speed), so most phones offer a virtual sensor which subtracts the constant acceleration (usually by taking into account the data from other sensors as well). This is what we call “Acceleration (without g)” and it will actually report an acceleration of zero while the phone is not accelerated.

Unfortunately, this sensor is not available on iPhones. While these phones have a physical light sensor to automatically adjust the brightness of the display, there is no direct access to this sensor for apps on these devices.

Usually, this should be the data from the GPS, but on iOS we cannot prevent the system from using location data from the mobile and WIFI networks as well.

Matthias Troiber has sent us an entire series of worksheets, which are currently available in German only.