One joule per second is equal to which of the following units?

The correct choice is one watt.

One joule per second is the definition of a watt, which is a unit of power in the International System of Units (SI). Power is defined as the rate at which energy is transferred or converted and is expressed in joules per second. Therefore, when energy is used at a rate of one joule every second, it is equivalent to one watt. Understanding this relationship is critical, as it helps in various applications, such as electrical engineering and energy management.

While one newton-metre per second also represents power, it’s more common in mechanical contexts, and its equivalency to watts is not as direct in terms of everyday calculations. The other choices, such as one kilogram per square meter and one kilowatt, either represent different dimensions or scales of power, but they do not define the basic unit of power as directly as one watt. A kilowatt is actually equal to 1,000 watts, which illustrates the relationship but is not equal to one joule per second itself.