Occupants of cars hit from behind, even at low speed, often suffer serious neck injury from whiplash. During a low‑speed rear‑end collision, a person's head suddenly pivots about the base of the neck through a 52∘52∘ angle, a motion that lasts 200 ms.200 ms. The distance from the base of the neck to the center of the head is typically about 20 cm,20 cm, and the head normally comprises about 6.0%6.0% of body weight. Model the motion of the head as having a uniform speed over the course of its pivot. Compute answers to two significant figures. What is the acceleration ?centacent of the head during the collision? ?cent=acent= m/s2m/s2 What force ?F does the neck exert on the head of a 70 kg70 kg person in the collision? Neglect the force of gravity on the head, and report the answer in units of both newtons and pounds. ?=F= NN ?=F= lbslbs Would headrests mounted to the backs of the car seats help protect against whiplash? Why or why not? Yes. A headrest applies an upward force on the head, along the direction of the neck, that cancels the downward force applied by the neck. Yes. A headrest ensures that both the head and the body experience the same forward force at roughly the same time. No. A headrest applies a mostly horizontal force to the head, so does not affect the mostly vertical force applied by the neck during whiplash. No. A headrest reduces the angle traversed by the head, not the speed of the head relative to the body, thus it does not affect the force that the neck applies to the head.
Occupants of cars hit from behind, even at low speed, often suffer serious neck injury from whiplash. During a low‑speed rear‑end collision, a person's head suddenly pivots about the base of the neck through a 52∘52∘ angle, a motion that lasts 200 ms.200 ms. The distance from the base of the neck to the center of the head is typically about 20 cm,20 cm, and the head normally comprises about 6.0%6.0% of body weight. Model the motion of the head as having a uniform speed over the course of its pivot. Compute answers to two significant figures. What is the acceleration ?centacent of the head during the collision? ?cent=acent= m/s2m/s2 What force ?F does the neck exert on the head of a 70 kg70 kg person in the collision? Neglect the force of gravity on the head, and report the answer in units of both newtons and pounds. ?=F= NN ?=F= lbslbs Would headrests mounted to the backs of the car seats help protect against whiplash? Why or why not? Yes. A headrest applies an upward force on the head, along the direction of the neck, that cancels the downward force applied by the neck. Yes. A headrest ensures that both the head and the body experience the same forward force at roughly the same time. No. A headrest applies a mostly horizontal force to the head, so does not affect the mostly vertical force applied by the neck during whiplash. No. A headrest reduces the angle traversed by the head, not the speed of the head relative to the body, thus it does not affect the force that the neck applies to the head.
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
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Occupants of cars hit from behind, even at low speed, often suffer serious neck injury from whiplash. During a low‑speed rear‑end collision, a person's head suddenly pivots about the base of the neck through a 52∘52∘ angle, a motion that lasts 200 ms.200 ms. The distance from the base of the neck to the center of the head is typically about 20 cm,20 cm, and the head normally comprises about 6.0%6.0% of body weight.
Model the motion of the head as having a uniform speed over the course of its pivot. Compute answers to two significant figures.
What is the acceleration ?centacent of the head during the collision?
?cent=acent=
m/s2m/s2
What force ?F does the neck exert on the head of a 70 kg70 kg person in the collision? Neglect the force of gravity on the head, and report the answer in units of both newtons and pounds.
?=F=
NN
?=F=
lbslbs
Would headrests mounted to the backs of the car seats help protect against whiplash? Why or why not?
Yes. A headrest applies an upward force on the head, along the direction of the neck, that cancels the downward force applied by the neck.
Yes. A headrest ensures that both the head and the body experience the same forward force at roughly the same time.
No. A headrest applies a mostly horizontal force to the head, so does not affect the mostly vertical force applied by the neck during whiplash.
No. A headrest reduces the angle traversed by the head, not the speed of the head relative to the body, thus it does not affect the force that the neck applies to the head.
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