A maintenance vehicle is tested on a dry, level track. The same driver and vehicle are used for both tests. The driver responds to the signal by applying the brakes as quickly as possible.
| Speed of vehicle (m/s) | Thinking distance (m) | Braking distance (m) |
|---|---|---|
| 10 | 7 | 10 |
| 20 | 14 | 40 |
Explain the effect of increasing the speed on the vehicle's stopping distance, using the results in the table. Predict how the braking distance would change if the vehicle travelled at 20 m/s on a loose gravel surface, and explain your prediction.