Final answer:
Bathroom scales are designed to measure weight but show mass by dividing the force reading by the acceleration due to gravity. Pushing down on a table while on a scale increases the force and reading. On the Moon, the scale would need recalibration to show correct mass as gravity is different.
Step-by-step explanation:
Understanding How Scales Measure Mass and Weight
Bathroom scales measure weight, which is the force of gravity acting on a mass. When you stand on a bathroom scale, it depresses slightly, and internal springs compress in proportion to your weight. Newton's second law of motion allows us to understand that this compression provides a measure of weight. However, the scale is calibrated to display your mass, by dividing the weight in newtons by the standard acceleration due to gravity (9.80 m/s2), resulting in a reading in kilograms. On the Moon, where gravity is weaker, a scale would not measure the same mass unless it is recalibrated, because the force of gravity, and therefore your weight, is different.
If you push down on a table while standing on the scale, the reading will increase because you are adding more force downward, which the scale interprets as increased weight. Scales are generally precise measurement tools, with some digital scales being able to measure mass to the nearest thousandth of a gram.