Answer: The motion is accelerated.
Step-by-step explanation: Given that the horse is walking along a straight line.
The horse travels 3 m in first second, so its speed is 3m/s.
In the next second, the horse travels 4 m, so its speed is 4 m/s.
In the third second, the horse travels 5 m, so its speed is 5 m/s.
Since the speed of the horse is increasing per second i.e., the speed in not constant, so the motion of the horse is accelerated.
