Assessment and Qualifications Alliance (AQA) GCSE Physics Practice Exam

The SI unit for speed is meters per second. This is the standard unit of measurement used in the International System of Units (SI), which is an internationally accepted system for measuring physical quantities. Speed is defined as the distance traveled per unit of time, and expressing this in meters per second aligns with the basic SI units where distance is measured in meters and time in seconds. This unit is particularly useful in scientific calculations and provides a clear and consistent basis for measuring speeds across various disciplines in physics.

In contrast, kilometers per hour, feet per minute, and miles per hour are all valid units of speed but are not part of the SI system. They are often used in everyday contexts or specific applications like driving or aviation, but for scientific accuracy and standardization, meters per second is the correct SI unit.