I have two different photographic flash units. One is rated in joules and one in "watt-seconds," which is commonly used for flash units. Looking at the mathematics, I see a joule is defined as a kg*m2/s2, while a watt is a kg*m2/s3. Therefore, a watt-second would be the same as a joule, since the seconds to the minus 3 power would become seconds to the minus 2 power when multiplied by seconds (overall > energy times time equals power).
Is my reasoning correct?? Any ideas why the industry would be using "watt-seconds" instead of joules? Paul
