Learn in the textbookDetection Devices (Light, Electromagnetic, and Motion Sensors)
DefinitionAn accelerometer (加速度センサー) detects how quickly an object's speed changes, which is its acceleration.
ExplanationAcceleration is the amount by which speed changes per unit of time. Besides changes in speed such as starting off or stopping suddenly, an accelerometer also senses the direction of gravity, which acts even when the device is still, so it can tell how the device is tilted. It is what lets a smartphone switch between portrait and landscape, and what lets a pedometer count the jolts of each step.
AnalogyIt is like a train passenger who knows the train is braking because their body is pulled forward.
Memory hookThe word itself says it: accelerating means changing speed. Cruise at a steady speed and the reading stays the same.