What is an accelerometer
Discover the concept of linear acceleration
Author:
Title 4
Learning objectives :
This activity allows students to discover how an accelerometer works by directly exploring its responses to different movements. It develops an intuitive understanding of acceleration as a vector quantity.
Concepts covered
Acceleration as a vector quantity, Relationship between force and acceleration, Coordinate systems and axes, MEMS sensors, Interpretation of time graphs
What students will do :
The student uses FizziQ's Linear Acceleration X and observes the variations of the graph as he moves his smartphone in different directions. By making movements to the right then to the left, fast or slow, it analyzes the sign and amplitude of the acceleration during the different phases of the movement. From his observations, the student establishes general rules on the relationship between the direction of movement, the force applied and the sign of acceleration.
What is required :
Smartphone with the FizziQ application, Clear space to carry out movements
Scientific background :
The accelerometer of a smartphone is a MEMS (Micro Electro Mechanical Systems) sensor that measures acceleration on three orthogonal axes (X, Y, Z). Its operating principle is based on a small mass suspended by microscopic springs. During acceleration, the inertia of this mass causes its relative movement relative to the sensor frame, a deformation measured electronically. The acceleration measured on the X axis corresponds to the change in speed along this axis. When moving the smartphone to the right, we typically observe three phases: 1) positive acceleration during the initial phase where the speed increases, 2) zero acceleration during the movement at constant speed, 3) negative acceleration when slowing down. This profile reverses for a movement to the left. These observations illustrate Newton's second law (F = ma): acceleration is proportional to the applied force and in the same direction. The maximum absolute value of acceleration generally appears at moments of sudden change: rapid start or sudden braking.