Consider the following actions : 1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously 2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive 3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode In how many of the above actions is the function of accelerometer required?

1. Action 1: Detection of a car crash/collision relies heavily on accelerometers. These sensors detect the rapid deceleration experienced during a crash, which triggers the deployment of airbags. The function of an accelerometer is required. 2. Action 2: Many laptops are equipped with accelerometers for accidental free fall detection. When the accelerometer detects the zero-gravity state of a free fall, it signals the system for the immediate turning off (parking) of the hard drive heads to prevent damage upon impact. The function of an accelerometer is required. 3. Action 3: Accelerometers are standard components in smartphones used for the detection of tilt and orientation relative to gravity. This data is used to automatically switch the display rotation between portrait and landscape mode. The function of an accelerometer is required. 4. Therefore, all three described actions require the function of an accelerometer.