Consider the following actions:1.Detection of car crash/collision which results in the deployment of airbags almost instantaneously2.Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive3.Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape modeIn how many of the above actions is the function of accelerometer required?

1. A

   Only one

   Only one. All three detections use an accelerometer.

2. B

   Only two

   Only two. Airbags, HDD free-fall and screen rotation all need acceleration / tilt sensing.

3. C

   All three

   All three. Crash pulse, free-fall, and portrait–landscape tilt.

4. D

   None

   None. MEMS accelerometers do exactly this.

Summary. Official key is (c) all three. An accelerometer senses proper acceleration: airbag crash detection, laptop free-fall (park the head), and phone tilt for display rotation. None of the three is outside that sensor.