To find the unit rate (speed) of the motorcycle, we can divide the total distance by the total time:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{500 \text{ miles}}{8 \text{ hours}} = 62.5 \text{ miles per hour} \]
Now, we compare this speed to the speed limit:
- The speed limit is 65 miles per hour.
- The motorcycle's speed is 62.5 miles per hour.
Since 62.5 miles per hour is less than 65 miles per hour, we conclude that the motorcycle is going slower than the speed limit.
So, the answer is: Slower than.