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?

Answer: C. All THREE actions require accelerometers. An accelerometer is a MEMS sensor that detects acceleration in one or more axes by measuring tiny movements of an internal mass relative to the device frame. (1) Car crash detection / airbag deployment: YES. Accelerometers detect the sudden deceleration during a collision and trigger airbag deployment in milliseconds. This is the primary application in vehicle safety systems. (2) Laptop free-fall detection / hard drive parking: YES. Accelerometers in laptops detect free-fall (g approaches 0) and park the read/write head to prevent disk damage on impact. This 'active hard drive protection' is common in business laptops. (3) Smartphone tilt for portrait/landscape rotation: YES. Accelerometers measure the orientation of the device relative to gravity. The OS uses this to rotate the display. All three are textbook accelerometer applications. Source: MEMS sensor technology references / standard electronics texts.