Engineers compare two passenger restraint systems using identical crash-test dummies. Each dummy has a mass of 75 kg and is moving at 18 m/s before being brought to rest.
| Restraint system | Stopping time in s | Contact area in m2\text{m}^2m2 |
|---|---|---|
| P: seat belt only | 0.090 | 0.015 |
| Q: seat belt and airbag | 0.25 | 0.060 |
Assume that the average resultant force exerted by each restraint system acts over the stated contact area.
Give one feature of the vehicle structure, other than a passenger restraint, that can reduce the risk of injury in a collision.
Calculate the average pressure exerted by restraint system Q on the dummy.
Explain why restraint system Q is expected to reduce the risk of injury more than restraint system P. Use data from the table in your answer.