Which instrument compares the mass of two objects?

Which instrument compares the mass of two objects?

• A. Pan Balance
• B. Digital Balance
• C. Stopwatch
• D. Ruler

Answer: (A)

Direct mass comparison is what this item tests. A pan balance is designed for that purpose: you place one object on each pan, and the beam becomes level only when the two masses are equal. If one side is heavier, that side tilts downward, showing which object has more mass and by how they relate in a direct, side-by-side way. A digital balance, while it can measure mass, gives a numeric value for a single object against a standard rather than directly comparing two unknown masses at once. A stopwatch and a ruler measure time and length, respectively, so they don’t fit the task of comparing masses.

Direct mass comparison is what this item tests. A pan balance is designed for that purpose: you place one object on each pan, and the beam becomes level only when the two masses are equal. If one side is heavier, that side tilts downward, showing which object has more mass and by how they relate in a direct, side-by-side way. A digital balance, while it can measure mass, gives a numeric value for a single object against a standard rather than directly comparing two unknown masses at once. A stopwatch and a ruler measure time and length, respectively, so they don’t fit the task of comparing masses.