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* BIO Dumbbell lift IA woman lifts a 3.6-kg dumbbell in each hand with her arm in a horizontal position at the side of her body and holds it there for 3 s (see Figure P8.53) What force does the deltoid muscle in her shoulder exert on the humerus bone while holding the dumbbell? The deltoid attaches 13 cm from the shoulder joint and makes a
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- BIO When a gymnast performing on the rings executes the iron cross, he maintains the position at rest shown in Figure P10.85a. In this maneuver, the gymnasts feet (not shown) are off the floor. The primary muscles involved in supporting this position are the latissimus dorsi (lats) and the pectoralis major (pecs). One of the rings exerts an upward fore Fh on a hand as shown in Figure P10.85b. The force Fs is exerted by the shoulder joint on the arm. The latissimus dorsi and pectoralis major muscles exert a total force Fm on the arm. (a) Using the information in the figure, find the magnitude of the force Fm. (b) Suppose an athlete in training cannot perform the iron cross but can hold a position similar to the figure in which the arms make a 45 angle with the horizontal rather than being horizontal. Why is this position easier for the athlete? Figure P10.85arrow_forwardTorque and the Two Conditions for Equilibrium 17. The arm in Figure P8.17 weighs 41.5 N. The force of gravity acting on the arm acts through point A. Determine the magnitudes of the tension force Ft, in the deltoid muscle and the force Fs exerted by the shoulder on the humerus (upper-arm bone) to hold the arm in the position shown. Figure P8.17arrow_forwardMany of the elements in horizontal-bar exercises can be modeled by representing the gymnast by four segments consisting of arms, torso (including the head), thighs, and lower legs, as shown in Figure P8.15a. Inertial parameters for a particular gymnast are as follows: Note that in Figure P8.l5a rcg is the distance to the center of gravity measured from the joint closest to the bar and the masses for the arms, thighs, and legs include both appendages. I is the moment of inertia of each segment about its center of gravity. Determine the distance from the bar to the center of gravity of the gymnast for the two positions shown in Figures P8.15b and P8.15c. Figure P8.15arrow_forward
- A bowling ball rolls up a ramp 0.5 m high without slipping to storage. It has an initial velocity of its center of mass of 3.0 m/s. (a) What is its velocity at the top of the ramp? (b) If the ramp is 1 m high does it make it to the top?arrow_forwardA 5.0-m-long,15-kg level plank is supported by two pivots that are resting on level ground at opposite ends of the plank. A 70-kg construction worker is standing 1.5 from the right pivot. What is the magnitude of the force of the left pivot on the plank? a. 80 N b. 130 N c. 180 N d. 230 N e. 280 Narrow_forwardIf you hold your arm outstretched with palm upward, as shown, the force to keep your arm from falling comes from your deltoid muscle. The arm of a typical person has mass 4.0 kg and the distances and angles shown in the figure.a. What force must the deltoid muscle provide to keep the arm in this position?b. By what factor does this force exceed the weight of the arm?arrow_forward
- Q2) Machine Curls and the Biceps Muscle. A woman performs seated machine curls to strengthen her biceps muscles (the figure below). She uses a weight of 10 kg. Horizontal distance between her elbows (A) and the bottom of the frictionless pulley (B) is 60 cm. Vertical distance between the same points is 20 cm. Determine the force exerted by the holding bar on the woman's hands when her arm is at 45° with the horizontal. At that moment, the weight has an upward acceleration of 3 m/s2. DB DIA 32cm 20cm PAB 45 60cmarrow_forwardView Policies Current Attempt in Progress Concept Simulation 9.1 illustrates how the forces can vary in problems of this type. A hiker, who weighs 668 N, is strolling through the woods and crosses a small horizontal bridge. The bridge is uniform, weighs 4590 N, and rests on two concrete supports, one on each end. He stops 1/6 of the way along the bridge. What is the magnitude of the force that a concrete support exerts on the bridge (a) at the near end and (b) at the far end? (a) Number i Units (b) Number Unitsarrow_forwardA5.4 kg cat and a 2.1 kg bowl of tuna fish are at opposite ends of the 4.0-m-long seesaw. (Figure 1) You may want to review (Pages 312 - 314). Part A How far to the left of the pivot must a 3.9 kg cat stand to keep the seesaw balanced? Express your answer to two significant figures and include the appropriate units. HÅ ? d = Value Units Submit Request Answer Provide Feedback Figure 1 of 1 > 2.0 m 2.0 marrow_forward
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