If that physical property is weight, you can use what is known as a load cell. [DegrawSt] uses four 50 kg load cells to create a bathroom scale using an Arduino.

This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute (RPM). You don’t need much… ...

Tronixstuff has a borderline insane tutorial series going, and as of now, 27 chapters have been published. It's essentially the Arduino Bible, but the two most recent additions in particular have ...