```
Speed = √(254.3 * Skid Length)
```
where:
- Speed is in feet per second (fps)
- Skid Length is the length of the skid mark in feet.
Here's an example of how to calculate the speed of a vehicle:
- If a skid mark is 100 feet long, then:
- Speed = √(254.3 * 100)
- Speed = √(25430)
- Speed = 159.4 fps
- To convert fps to mph, multiply the speed by 0.682.
- Speed = 159.4 * 0.682
- Speed = 108.6 mph