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Even when the head is held erect, as in Figure 9.41, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. (a) Calculate the force exerted by these muscles using the information in the figure. (b) What is the force exerted by the pivot on the head?
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- Even when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 43 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that x1 = 4.9 cm, x2 = 2.7 cm, and F = 43 N. W FM = A M What is the force F¡ exerted by the pivot on the head? F = Narrow_forwardEven when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 43 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that x1 = 5.1 cm, x2 = 2.7 cm, and |Fw = 43 N. N What is the force Fj exerted by the pivot on the head? F; = N Question Credit: OpenStax College Physicsarrow_forwardEven when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 55 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that 5.1 cm, x2 2.5 cm, and Fw = 55 N. X1 = -26.96 A F N M = Incorrect M What is the force Fj exerted by the pivot on the head? -81.96 Fj = N Incorrectarrow_forward
- Even when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 55 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that x1 = 4.9 cm, x2 = 1.9 cm, and Fw = 55 N. %3D W X, %3D M M What is the force F exerted by the pivot on the head? |F. W %3Darrow_forwardEven when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 55 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that x1 = 5.1 cm, x2 = 1.9 cm, and Fw = 55 N. FM = N What is the force Fj exerted by the pivot on the head? F = Narrow_forwardEven when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 55 N, calculate the force exerted by the muscles FM using the information in the figure. Assume that x1 = 5.1 cm, x2 = 1.9 cm, and |Fw = 55 N. W EM = FM A N M What is the force Fj exerted by the pivot on the head? F, N = Question Credit: OpenStax College Physicsarrow_forward
- Even when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint, Point A). The muscles at the back of the neck should, therefore, exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. If the head weighs 51 N, calculate the force exerted by the muscles Fm using the information in the figure. Assume that x1=5.3 cm, x2 = 2.5 cm, and |Fw|= 51 N. What is the force Fj exerted by the pivot on the head? Fj=arrow_forwardEven when the head is held erect, as in the figure below, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. Calculate the force (in N) exerted by these muscles. (Assume w = 55 N, r1 = 4.8 cm, and r2 = 2.9 cm.) magnitude N direction (upward, downward, to the left, or to the right) What is the force (in N) exerted by the pivot on the head? magnitude N direction (upward, downward, to the left, or to the right)arrow_forwardYou can find the center of gravity of a meter stick by resting it horizontally on your two index fingers, and then slowly drawing your fingers together. First the meter stick will slip on one finger, and then on the other, but eventually the fingers meet at the CG. Why does this work?arrow_forward
- Even when the head is held erect, as shown in the figure, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in class. Part (a) If the head has a weight of 48.3 N, calculate the force in units of newtons exerted by these muscles using the information in the figure. Part (b) What is the force in newtons exerted by the pivot on the head?arrow_forwardA person bending forward to lift a load "with his back" (Figure a) rather than with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a W-195-N object. The spine and upper body are represented as a uniform horizontal rod of weight W-295 N pivoted at the base of the spine. The erector spinalls muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0° Back muscle Pivot R₂ T120 T W W₂ 0 (a) Find the tension in the back muscle. KN D (b) Find the compressional force in the spine. (Enter the magnitude.) KNarrow_forwardYou can find the center of gravity of a long ruler by resting it horizontally on your two index fingers, and then slowly drawing your fingers together. First the ruler will slip on one finger, and then on the other, but eventually the fingers meet at the CG. Why does this workarrow_forward
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