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*BIO While browsing books on neurophysiology, you come across a book published in 1967 by Soviet neurophysiologist Nikolai Aleksandrovich Bernstein, The Co-ordination and Regulation of Movements, in which he describes a technique to determine the mass of a part of the human body if the position of the center of mass of that body part is known. His technique for determining the mass of the forearm is described as follows: The person lies on a support board, as shown in Figure P8.57. Two readings of the scale are taken: first with the forearm held in position 1 (
(a) First, without deriving the expression, evaluate it to see if it is reasonable. Are the units correct? Is the sign of the expression positive? Are qualitative dependences reasonable? (b) Now derive the expression. (c) Why do you think it is important to place the support board on knife edges instead of rigid blocks?
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- A One end of a metal rod of weight Fg and length L presses against a corner between a wall and the floor (Fig. P14.64). A rope is attached to the other end of the rod. Find the magnitude of the tension in the rope if the angle between the rod and the rope is 90.arrow_forwardA 2.45-kg ball is shot into a 0.450-kg box that is at rest on a frictionless, horizontal table (Fig. P11.25); after the collision, the ball is embedded in the box. The box is attached to a 0.30-m rope that is attached to the table on the other end. The balls initial velocity is perpendicular to the rope as shown. If the balls initial speed before impact is 13.5 m/s, what is the tension in the rope after the collision? FIGURE P11.25arrow_forwardA person carries a plank of wood 2.00 m long with one hand pushing it down at one end with a force F1 and the other hand holding it up with a force F2 at a distance of 0.500 m from the same end of the plank. If the plank has mass 20.0 kg and the center of mass of the plank is in the middle of the plank, what are the magnitudes of the forces F1 and F2? a. F1 = 392.4 N, F2 = 196.2 N b. F1 = 392.4 N, F2 = 392.4 N c. F1 = 196.2 N, F2 = 392.4 N d. F1 = 196.2 N, F2 = 196.2 Narrow_forward
- I Re You're carrying a 3.6-m-long, 24 kg pole to a construction site when you decide to stop for a rest. You place one end of the pole on a fence post and hold the other end of the pole 35 cm from its tip. Part A For the steps and strategies involved in solving a similar problem, you may view a Video Tutor Solution. How much force must you exert to keep the pole motionless in a horizontal position? Express your answer in newtons. Vo AE F = N Submit Previous Answers Request Answerarrow_forwardA. Explain why placing your hands behind your head rather than placing them on your stomach makes sit-ups more difficult. B. Explain why it is easier (it requires a smaller force) to open a large jar than a small one.arrow_forwardIf forces are acting on a rigid body so that it has zero kinetic energy, then all forces will pass through the centre of mass and have a vector sum of zero. True or False? a) True b) Falsearrow_forward
- A meter stick balances horizontally on a knife-edge at the 50.0 cm mark. With two 3.04 g coins stacked over the 35.1 cm mark, the stick is found to balance at the 44.8 cm mark. What is the mass of the meter stick? Number i Unitsarrow_forwardUse the following information to estimate the mass of a surfboard. Maximum displacement of the boy is 0.9 m Maximum displacement of the surfboard is 1.3 m Assume the boy and surfboard system are isolated. The mass of the boy is 33.3 kg. The formula for the center of mass is… m1x1+m2x2/m1+m2arrow_forwardA rod of length L is composed of a uniform length ½ L of wood whose mass is mw, and a uniform length ½ L of brass whose mass is mb. Find I for the rod about an axis perpendicular to the rod and through its center. Repeat for a parallel axis through the woodarrow_forward
- An 85-kg basketball player does a series of push-ups to strengthen his arm and chest muscles. If both feet and exert the same force and both palms do, likewise, determine the force that the floor exerts of on each of his feet and on each hand. Assume that his center of mass is 0.920 m from the top of his head. _2.10 m 30.0 cm→arrow_forwardA slender rod with length L has a mass per unit length that varies with distance from the left-hand end, where = 0, according to dm/dx = y, where y has units of kg/m². For related problemsolving tips and strategies, you may want to view a Video Tutor Solution of Uniform sphere with radius r, axis through center. Part A Calculate the total mass of the rod in terms of Y and L. Express your answer terms of the variables y and L. ΓΙΑΣ. 6 IXI ? X. 10m ⒸHAR M= Submit Previous Answers Request Answer * Incorrect; Try Again; 3 attempts remaining The correct answer does not depend on: ML. Part B Use I = fr² dm to calculate the moment of inertia of the rod for an axis at the left-hand end, perpendicular to the rod. Use the expression you derived in part A to express I in terms of M and L. Express your answer in terms of the variables M and L. ΠΙΑΣΦΗ I = Submit Request Answer Part C Repeat part B for an axis at the right-hand end of the rod. Express your answer in terms of the variables M and L.…arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning