The symbol of a simple unprefixed SI unit has been left off of each measurement in the table below. Fill in the missing unit symbols. The mass of a U.S. quarter = 6.5 g. The length of a pencil = 0.15 m. The width of a two-lane road = 10 m. The volume of beer in a six pack = 1.2 L.
The Correct Answer and Explanation is:
Correct Units for Each Measurement:
- The mass of a U.S. quarter = 6.5 g
- The length of a pencil = 0.15 m
- The width of a two-lane road = 10 m
- The volume of beer in a six-pack = 1.2 L
Explanation
SI units (International System of Units) are the standard units used in scientific and most everyday measurements globally. When we talk about “unprefixed SI units,” we refer to the base SI units without metric prefixes like kilo-, milli-, or centi-. The base SI units relevant to this context are:
- Meter (m) for length
- Gram (g) for mass (Note: technically, the SI base unit for mass is the kilogram (kg), but gram (g) is often used for smaller masses and is widely accepted)
- Liter (L) for volume (Note: while not a base SI unit, the liter is commonly used alongside SI units for measuring volume)
Let’s examine each measurement:
- Mass of a U.S. quarter = 6.5 g
The mass of small objects like coins is best measured in grams. Since a quarter weighs only a few grams, “g” is the most suitable unit. - Length of a pencil = 0.15 m
Length is a base SI unit measured in meters (m). A pencil is around 15 centimeters or 0.15 meters long, making “m” appropriate. - Width of a two-lane road = 10 m
The width of roads is usually several meters wide. Ten meters (m) is a typical dimension, so “m” is again correct. - Volume of beer in a six-pack = 1.2 L
Volume in daily life, especially for liquids, is commonly measured in liters (L). A six-pack of 355 mL (standard can size) equals 2.13 L, so 1.2 L may suggest smaller cans. “L” is the suitable unit.
Using the correct SI unit ensures clarity, precision, and international understanding across scientific and practical applications.
