Which unit is used for the final velocity in the velocity example?

• A. m/s
• B. ft/s
• C. in/s
• D. cm/s

Answer: (B)

Velocity is a rate of change of position, so its units are a length unit divided by a time unit. In the velocity example, distances are given in feet and time in seconds, so the final velocity must be expressed in feet per second. This keeps the unit consistent with how the data were measured. If the problem used inches or meters, the corresponding units would be inches per second or meters per second, respectively.