Yahoo 知識+ 將於 2021 年 5 月 4 日 (美國東岸時間) 停止服務，而 Yahoo 知識+ 網站現已轉為僅限瀏覽模式。其他 Yahoo 資產或服務，或你的 Yahoo 帳戶將不會有任何變更。你可以在此服務中心網頁進一步了解 Yahoo 知識+ 停止服務的事宜，以及了解如何下載你的資料。
Physics--Momentum(Car safety) Urgent(15 marks)
1. How the air bags and bumpers which installed at the front and rear parts of vehicles can reduce the impulsive force acting on the occupants during the collisions?
2. When a babysitting is installed inside a car with air bags, what is the special features of it?
3. A company invented a new car that can reduce the causualty in car accidents. If the car hits a pedestrian, the sensor in the front part of the car is alerted and the front cover springs upwards. How to explain this can reduce the injuries of the pedestrian??
Reference: Physics for tomorrow 2(manhattan) P.161 STS Corner 1 Q4,5,6
- hlyungLv 71 十年前最愛解答
1. Since impulsive force=change in momentum/impact time, the air bags and bumpers are used to increase the impact time and hence reduce the implusive force acting on the occupants.
2. It is also used to increase the impact time and hence reduce the force acting on the baby.
3. Since momentum=mass x velocity, this can reduce the mass of the car and hence reduce the momentum change and impulsive force acting on the pedestrian.