What it is and the problem it solves
An accelerometer is a sensor that measures proper acceleration — the push or pull an object feels relative to free fall. It solves the problem of quantifying felt force in moving or gravitating systems.
How it works
It measures proper acceleration — the acceleration an object experiences relative to free fall. A damped proof mass on a spring deflects under inertial force. Newton’s third law causes compression or extension; Hooke’s law converts that deflection into acceleration using known spring constant and mass.
What works
At rest on Earth, it reads ~9.81 m/s² upward. In free fall, it reads zero. This behaviour is consistent, repeatable, and rooted in Einstein’s equivalence principle.
What does not
It does not measure coordinate acceleration directly. It cannot distinguish gravity from upward acceleration without external reference. It gives no velocity or position without integration — which accumulates error.
What it changes
It redefines measurement of motion: acceleration becomes observable without external landmarks. It grounds inertial navigation, structural monitoring, and device orientation in physics, not geometry.
Is it worth your time
Yes — if your work involves motion sensing, inertial navigation, or distinguishing gravitational from kinematic acceleration. It is foundational, not optional, but requires calibration for context-specific interpretation.