Final answer:
The angular momentum of a particle moving at uniform speed in a circular path is given by 'c. mvr'. Angular momentum is a central concept in the study of rotational dynamics within physics, and it can vary with time depending on external torques.
Step-by-step explanation:
The student is inquiring about the concept of angular momentum, which is a fundamental topic in the field of physics, specifically within the study of rotational dynamics. The answer to the original question posed by the student would be that the angular momentum of a particle of mass m, moving at a uniform speed v in a circle of radius r, about the center of the circle, can be given by the expression L = mvr, and therefore the correct choice would be 'c. mvr'. This relationship expresses the momentum of a point mass in rotational motion and is a key concept when analyzing systems undergoing circular motion.
In a more general context, angular momentum (L) can vary with time if the net external torque on the system is nonzero. As such, if we have a time-dependent angular momentum function, we would be able to find the torque on the particle by taking the derivative of the angular momentum with respect to time. Similarly, we could find out the particle's angular velocity if other relevant information, like the moment of inertia, is provided.