Given a scientific question, generate a correct answer to it.

Example Input: Meters, such as those in analog fuel gauges on a car, are a common application of magnetic torque on a current-carrying what?
Example Output: loop

Example Input: What is the term for a loop in which a product feeds back to control its own production?
Example Output: feedback mechanism

Example Input: What is friction that acts on objects that are moving through a fluid?
Example Output:
fluid friction