A boy sits on the edge of a stationary merry-go-round. His dog runs along the ground and jumps into his arms in such a way that the merry-go-round starts to spin. After the dog has landed and the merry-go-round is spinning,

It could be inferred from the question that it's a scenario of an example of angular momentum.

Explanation:

Put simply, angular momentum is the momentum of an object (the boy) that is either rotating or in circular motion and is equal to the product of the moment of inertia and the angular velocity of the object.

The results of the external force (the dog jumping on the boy) implies that both the merry-go-round and the dog have non-zero angular momentum around the merry-go-round axle.