Final answer:
According to Newton's third law of motion, when a dog catches a frisbee, the dog exerts a force on the frisbee, and the frisbee exerts an equal and opposite force on the dog. This force allows the dog to catch the frisbee.
Step-by-step explanation:
Newtons's third law of motion states that whenever a first object exerts a force on a second object, the first object experiences a force equal in magnitude but opposite in direction. Applying this law to a dog catching a frisbee, when the dog exerts a force on the frisbee by jumping in the air and biting it, the frisbee exerts an equal and opposite force on the dog. This reactive force allows the dog to catch the frisbee by providing the necessary propulsion and stability.