Travelling at a constant speed of 70 mph, it would take about 7 hours, 8 minutes and 34 seconds to drive 500 miles.
The formula to calculate the time required to ride a fixed distance in a given average speed is Time = Distance ÷ Speed.
When you have constant speed, the same formula pops up over and over again, and that's the formula that connects distance, speed and time.
Distance = Speed x Time
Time = Distance/Speed
Speed = Distance/Time
You can also use these online Speed Distance Time Calculators to easily calculate average speed to ride a fixed distance in a given time, time required to ride a fixed distance in a given average speed and distance covered from average speed and time elapsed.