In thrill machine rides at amusement parks ,there can be an acceleration of 3g or more .But without head rests ,acceleration like this would not be safe.think why not?
6 answers
If your body takes off at 3 g, it tries to pull your head along. The force in Newtons on your neck is then the mass of your head in kg * 3 * 9.8 m/s^2 or three times the weight of your head. Neck breaks, dead.
when our body takes off at 3g of acceleration,it will cause the neck to move also along with the whole body.A forcful jerk can cause a serious injury to our neck,That's why without head rest,we are not safe
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It is because head rest helps the head to accelerate with same rate as that of the remaining body. Without Head rest it is not safe.
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If your body moves with acceleration 3g or more then your neck is not able to move your head along with the body. The neck gets sudden jerks to move your head this jerk can broke your neck. To avoid this we use headrest.