Which pair of units measures the same quantity?

• A. Joule and Watt
• B. Newton and Joule
• C. Calorie and Liter
• D. Calorie and Joule

Answer: (D)

This question tests the idea that different units can measure the same physical quantity. A joule is the SI unit of energy, and a calorie is another unit used to express energy (in chemistry and nutrition). Because both units quantify energy, they measure the same quantity.

The other pairings mix different kinds of quantities: a watt is a unit of power (energy per time), a newton is a unit of force (and energy relates to force via work, but they aren’t the same quantity), and a liter is a unit of volume. So they don’t measure energy in the same way.

Therefore, calorie and joule are the pair that measure the same quantity.