Final answer:
The subject of this question is Physics. The correct answer is A) Angular momentum.
Step-by-step explanation:
The subject of this question is Physics. The question asks about the concept that corresponds to a 30 kg child swinging at the end of a 5.0-meter long rope. In this case, the correct answer is A) Angular momentum.
Angular momentum is a property of rotating objects, and it is defined as the product of the object's moment of inertia and its angular velocity. When the child swings at the end of a rope, they are experiencing circular motion, and therefore, angular momentum is involved. The angular momentum of the child can be calculated using the equation L = Iω, where L is the angular momentum, I is the moment of inertia, and ω is the angular velocity.