Final answer:
The dog is running at a speed of 5 meters per second (m/s), so the correct answer is option d. 5 m/s.
Step-by-step explanation:
The speed of the dog running after the ball can be calculated by dividing the distance it covers by the time taken. We use the following formula to get the speed:
Speed = Distance / Time
Given:
- Distance = 45 meters
- Time = 9 seconds
Thus, the speed of the dog is:
Speed = 45 meters / 9 seconds
Speed = 5 meters per second (m/s).
Therefore, option d. 5 m/s is the correct answer.