Which of the following is not a unit of work?

Work is defined in physics as the transfer of energy that occurs when a force is applied over a distance. The standard unit of work in the International System of Units (SI) is the joule (J), which is equivalent to one newton of force applied over a distance of one meter.

The joule itself is a basic unit, so it is indeed a unit of work. Similarly, the newton-meter is a derived unit that also represents work because it reflects the work done when a force of one newton moves an object one meter. The kilowatt-hour is a unit of energy, commonly used in electrical contexts, and is also associated with work, as it represents energy consumed over time, which can ultimately be converted to do work.

In contrast, the unit J⋅m is not a standard unit of work. While it involves joules and meters, it does not conform to the definition of work in physics. Instead, it might imply an exponential relationship that does not apply in this context. Thus, it is characterized as not being a proper unit of work, validating why this choice is correct.