4. What are the basic scientific principles the engineers who designed the digital scales would have needed to understand to design this tool? Choose all that apply.
A. electric currents
B. physical properties of metals
C. influence of gravitational force on objects
D. physical and chemical properties of materials used in building circuits

A, C and D

Explanation:

A digital scale is a measuring device used to measure the weight of an object. Unlike the mechanical version, the digital scale displays the numeric value of an object weight on a screen, that is, it does not use any mechanical part like a pointer.

To design this scale, the engineers heard to understand the principles of electric current which powers the device, the influence of gravitational force on objects for which a sensor is used to collect the weight of objects and convert it to digits, and the physical and chemical properties of materials used in building the digital scale circuits.