Which of the following SI units would be most appropriate to describe the width of a small piece of metal?

• A. millimeter (mm)
• B. liter (L)
• C. second (s)
• D. kilogram (kg)

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the physical quantity being measured. The problem asks for the unit to describe the width of a small piece of metal, which is a measure of length or distance.
2. Step 2: Review the given units and identify their physical quantities: liter (L) measures volume, second (s) measures time, kilogram (kg) measures mass, and millimeter (mm) measures length.
3. Step 3: Since width is a length measurement, eliminate units that do not measure length (liter, second, kilogram).
4. Step 4: Among length units, millimeter (mm) is appropriate for small dimensions because it is a subunit of the meter (1 mm = 0.001 m), suitable for measuring small objects.
5. Step 5: Conclude that the most appropriate SI unit to describe the width of a small piece of metal is the millimeter (mm).