That statement is not entirely accurate. While it's true that the impact force increases significantly with speed, it's not a simple linear relationship.

Here's why:

* Kinetic Energy: The force of impact is directly related to the kinetic energy of the vehicle. Kinetic energy is calculated as 1/2 * mass * velocity². This means kinetic energy is proportional to the square of the velocity.

* Doubling the Speed: If you double the speed from 10 mph to 20 mph, the kinetic energy increases by a factor of four (2² = 4). However, the impact force itself is not directly the same as kinetic energy.

* Impact Time: Impact force also depends on the time it takes for the object to come to a stop. A shorter impact time leads to a higher force. This is why crumple zones in cars are designed to extend the impact time and reduce the force on occupants.

Therefore, while the force of impact is greater at 20 mph than at 10 mph, it's not exactly four times greater. The actual increase in force is more complex and depends on factors like impact time and how the vehicle deforms.

It's crucial to remember that even a small increase in speed can result in a significant increase in the severity of an impact.