Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: The optical or refractive type of this quantity is measured in diopters and measures the ability of a device to focus light. A non-standard unit for this quantity is the ton of refrigeration, and in systems with flow, it is equal to the product of flow rate and pressure. Radiative intensity or energy flux is defined as luminosity or this quantity per unit area. In rotational systems, it can be calculated as the dot product of torque and angular velocity, while in kinematics it is simply given by force times velocity. For 10 points, name this physical quantity equal to the work done per unit time, often measured in Watts.
A:
Science