4. What are the basic scientific principles the engineers who designed the digital scales would have needed to understand to design this tool? Circle the correct answer(s).
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
Houghton Mifflin Harcourt

the correct choice is a .

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i believe the answer is a hope it and is correct

chemical energy --> gravitational potential energy --> kinetic energy --> elastic potential energy --> gravitational potential energy

explanation:

when emma starts the hike, the chemical energy stored in her body is used to climb up the mountain, and so she gains gravitational potential energy (because at the end, she will be at a higher height h above the ground). then she goes bungee jumping: as she falls, this gravitational potential energy is converted into kinetic energy (because her speed increases as she falls down), until the point when the rope stretches, and she stops moving. at that moment, all the kinetic energy is converted into elastic potential energy due to the stretching of the rope. then, this energy is released because the rope returns to its natural length, and emma gains a small increase in altitude , so she gains some gravitational potential energy.