Final answer:
A scale is a measuring instrument used to compare weight or mass. A bathroom scale measures weight by compressing springs, while a balance scale compares the weight of two objects. Gravity affects the measurements of a scale on the moon.
Step-by-step explanation:
A scale is a measuring instrument that compares the weight or mass of an object to a known reference weight or mass. It is used to determine the weight or mass of unknown objects by balancing them against known weights or masses.
In the case of a bathroom scale, it measures the weight of a person by compressing springs that are calibrated to display mass in kilograms. On the moon, the scale would detect a different mass due to the difference in gravitational force.
In the case of a balance scale, it compares the weight of two objects by using a standard weight on one side and the unknown weight on the other side. The balance scale would still be level on the moon because gravity is uniform there as well.