Criterion D in Practice: Weighing the Safety Impact of Technology (Crumple Zones & Electric Vehicles)
Criterion D asks you to step back from the science and judge its impact. The strongest answers do not just list pros and cons — they look at the same technology through several lenses and reach a reasoned conclusion. Vehicle safety is a perfect case study, because it mixes physics, engineering, the environment and everyday life.
Try it yourself: choose a pathway (crumple zones or electric vehicles) and work through five thinking strands, earning badges for well-supported ideas.
Case 1: crumple zones
A crumple zone is a part of a car designed to deform in a crash. The science is impulse: the change in momentum is fixed by the car's mass and speed, but force = change in momentum ÷ time, so by making the stopping time longer the crumple zone reduces the force on the passengers. Explaining that link, rather than just saying "it absorbs the impact", is what shows understanding.
Case 2: electric vehicles
Electric vehicles produce no exhaust emissions where they are driven, which improves local air quality. But the full picture includes how the electricity is generated, mining the materials for batteries, and what happens to batteries at the end of their life. Weighing those together is a genuine evaluation, not a slogan.
Five lenses for a balanced answer
Look at the technology from several viewpoints, and give a specific point for each:
- •Personal — how it affects an individual's safety, cost or choices.
- •Local — the effect on a community, town or school.
- •Global — the wider effect on the planet or across countries.
- •Critical — the strengths, limits and who is affected unequally.
- •Sustainable — whether it can continue without harming future generations.
Reaching a justified conclusion
End with a clear judgement and say why: which effects outweigh which, and what evidence supports that. Answers that stay neutral ("there are good and bad points") stay in the middle bands; a supported conclusion reaches the top.
Frequently asked questions
It increases the time over which the car stops, and since force equals change in momentum divided by time, a longer time means a smaller force on the occupants.
They remove exhaust emissions locally, but their overall impact depends on how the electricity is generated and how batteries are made and disposed of.
Explain the science accurately, discuss impacts from several perspectives with specific evidence, and finish with a justified conclusion.