College Physics: A Strategic Approach
3rd Edition
ISBN: 9780321907233
Author: Field
Publisher: YUZU
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Chapter 8, Problem 6CQ
To determine
To find: The point of center of gravity for the two people shown in Figure Q8.6 in the textbook.
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Chapter 8 Solutions
College Physics: A Strategic Approach
Ch. 8 - An object is acted upon by two (and only two)...Ch. 8 - Prob. 2CQCh. 8 - Could a ladder on a level floor lean against a...Ch. 8 - If you are using a rope to raise a tall mast,...Ch. 8 - Prob. 5CQCh. 8 - Prob. 6CQCh. 8 - Prob. 7CQCh. 8 - A spring exerts a 10 N force after being stretched...Ch. 8 - The left end of a spring is attached to a wall....Ch. 8 - A spring is attached to the floor and pulled...
Ch. 8 - A typical mattress has a network of springs that...Ch. 8 - Take a spring and cut it in half to make two...Ch. 8 - A wire is stretched right to its breaking point by...Ch. 8 - Steel nails are rigid and unbending. Steel wool is...Ch. 8 - The rod in Figure Q8.15 pivots around an axle at...Ch. 8 - Two children hold opposite ends of a lightweight,...Ch. 8 - Prob. 17MCQCh. 8 - Prob. 18MCQCh. 8 - Prob. 19MCQCh. 8 - Prob. 20MCQCh. 8 - Prob. 21MCQCh. 8 - Prob. 22MCQCh. 8 - You have a heavy piece of equipment hanging from a...Ch. 8 - Prob. 24MCQCh. 8 - Prob. 1PCh. 8 - Prob. 2PCh. 8 - Prob. 3PCh. 8 - Prob. 4PCh. 8 - Youre carrying a 3.6-m-long, 25 kg pole to a...Ch. 8 - Prob. 6PCh. 8 - How much torque must the pin exert to keep the rod...Ch. 8 - Prob. 8PCh. 8 - Prob. 9PCh. 8 - Consider the procedure for measuring a womans...Ch. 8 - Prob. 11PCh. 8 - Prob. 12PCh. 8 - Prob. 13PCh. 8 - Prob. 14PCh. 8 - Prob. 15PCh. 8 - Prob. 16PCh. 8 - Prob. 17PCh. 8 - The stability of a vehicle is often rated by the...Ch. 8 - You want to slowly push a stiff board across a 20...Ch. 8 - Prob. 20PCh. 8 - A car manufacturer claims that you can drive its...Ch. 8 - Prob. 22PCh. 8 - One end of a spring is attached to a wall. A 25 N...Ch. 8 - An orthodontic spring, connected between the upper...Ch. 8 - Experiments using optical tweezers measure the...Ch. 8 - A spring has an unstretched length of 10 cm. It...Ch. 8 - One end of a 10-cm-long spring is attached to the...Ch. 8 - A spring stretches 5.0 cm when a 0.20 kg block is...Ch. 8 - A 1.2 kg block is hung from a vertical spring,...Ch. 8 - You need to make a spring scale to measure the...Ch. 8 - A force stretches a wire by 1.0 mm. a. A second...Ch. 8 - What hanging mass will stretch a 2.0-m-long,...Ch. 8 - How much force does it take to stretch a...Ch. 8 - An 80-cm-long, 1.0-mm-diameter steel guitar string...Ch. 8 - A student is testing a 1.0 m length of...Ch. 8 - A 1.2-m-long steel rod with a diameter of 0.50 cm...Ch. 8 - A mineshaft has an ore elevator hung from a single...Ch. 8 - The normal force of the ground on the foot can...Ch. 8 - A three-legged wooden bar stool made out of solid...Ch. 8 - Prob. 40PCh. 8 - A glass optical fiber in a communications system...Ch. 8 - The Achilles tendon connects the muscles in your...Ch. 8 - Prob. 43GPCh. 8 - Prob. 44GPCh. 8 - Using the information in Figure 8.2, calculate the...Ch. 8 - A woman weighing 580 N does a pushup from her...Ch. 8 - Prob. 47GPCh. 8 - Prob. 48GPCh. 8 - Prob. 49GPCh. 8 - The wheel of mass m in Figure P8.50 is pulled on...Ch. 8 - A 5.0 kg mass hanging from a spring scale is...Ch. 8 - Two identical, side-by-side springs with spring...Ch. 8 - Two springs have the same equilibrium length but...Ch. 8 - Figure P8.54 shows two springs attached to a block...Ch. 8 - A 60 kg student is standing atop a spring in an...Ch. 8 - A 25 kg child bounces on a pogo stick. The pogo...Ch. 8 - Figure P8.57 shows a lightweight plank supported...Ch. 8 - In the hammer throw, an athlete spins a heavy mass...Ch. 8 - There is a disk of cartilage between each pair of...Ch. 8 - In Example 8.1, the tension in the biceps tendon...Ch. 8 - Larger animals have sturdier bones than smaller...Ch. 8 - Orb spiders make silk with a typical diameter of...Ch. 8 - Prob. 63MSPPCh. 8 - Prob. 64MSPPCh. 8 - Prob. 65MSPP
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- Torque 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_forwardBIO 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_forwardThe fishing pole in Figure P10.28 makes an angle of 20.0 with the horizontal. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the anglers hand if the fish pulls on the fishing line with a force F = 100 N at an angle 37.0 below the horizontal? The force is applied at a point 2.00 in from the anglers hands.arrow_forward
- A cook holds a 2.00-kg carton of milk at arm's length P8.19). What force FB must be exerted by the biceps muscle? (Ignore the weight of the forearm.) Figure P8.19arrow_forwardThe Iron Cross When a gymnast weighing 750 N executes the iron cross as in Figure lN.91a, the primary muscles involved in supporting this position are the latissimus dorsi (lats") and the pectoralis major (pecs"). The rings exert an upward force on the aims and support the weight of the gymnast. The force exerted by the shoulder joint on the arm is labeled Fs, while the two muscles exert a total force Fw on the arm. Estimate the magnitude of the force Fw. Note that one ring supports half the weight of the gymnast, which is 375 N as indicated in Figure P8.91b. Assume that the force Fw acts at an angle of 45 below the horizontal at a distance of 4.0 cm from the shoulder joint In your estimate, take the distance from the shoulder joint to the hand to be L = 70 cm and ignore the weight of the arm.arrow_forwardThe main muscles that hold your head upright attach to your spine in back of the point where your head pivots on your neck. Figure P8.66 shows typical numbers for the distance from the pivot to the muscle attachment point and the distance from the pivot to the center of gravity of the head. The muscles pull down to keep your head upright. If the muscle relaxes—if, for instance, you doze in one of your classes besides Physics—your head tips forward. In the questions that follow, assume that your head has a mass of 4.8 kg, and that you maintain the relative angle between your head and your spine. a. With the head held level, as shown, what muscle force is needed to keep a 4.8 kg head upright?b. If you tip your body forward so that your spine is level with the ground, what muscle force is needed to keep your head in the same orientation relative to the spine?c. If you tip your body backward, you will reach a point where no muscle force is needed to keep your head upright. For the…arrow_forward
- What happens to the center of gravity of a person under the following situations? a) His upper right extremity is amputated. b) He carries all his books using the right arm only.arrow_forwardWhen you bend over, a series of large muscles, the erector spinae, pull on your spine to hold you up. Figure shows a simplified model of the spine as a rod of length L that pivots at its lower end. In this model, the center of gravity of the 320 N weight of the upper torso is at the center of the spine. The 160 N weight of the head and arms acts at the top of the spine. The erector spinae muscles are modeled as a single muscle that acts at an 12° angle to the spine. Suppose the person shown bends over to an angle of 30° from the horizontal. a. What is the tension in the erector muscle? Hint: Align your x-axis with the axis of the spine.b. A force from the pelvic girdle acts on the base of the spine. What is the component of this force in the direction of the spine? (This large force is the cause of many back injuries).arrow_forwardIf you are using a rope to raise a tall mast, attaching the rope to the middle of the mast as in Q8.3a gives a very small torque about the base of the mast when the mast is at a shallow angle. You can get a larger torque by adding a pole with a pulley on top, as in Q8.3b. Draw a diagram showing all of the forces acting on the mast and explain why, for the same tension in the rope, adding this pole increases the torque on the mast.arrow_forward
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