Question: Figure CQ10.14 shows a metal washer

> A model airplane with mass 0.750 kg is tethered by a wire so that it flies in a circle 30.0 m in radius. The airplane engine provides a net thrust of 0.800 N perpendicular to the tethering wire. (a) Find the torque the net thrust produces about the cente

> A potter’s wheel having a radius of 0.50 m and a moment of inertia of 12 kg · m2 is rotating freely at 50 rev/min. The potter can stop the wheel in 6.0 s by pressing a wet rag against the rim and exerting a radially inward force of 70 N. Find the effecti

> An approximate model for a ceiling fan consists of a cylindrical disk with four thin rods extending from the disk’s center, as in Figure P8.41. The disk has mass 2.50 kg and radius 0.200 m. Each rod has mass 0.850 kg and is 0.750 m long

> Suppose you have one cubic meter of gold, two cubic meters of silver, and six cubic meters of aluminum. Rank them by mass, from smallest to largest. (a) Gold, aluminum, silver (b) Gold, silver, aluminum (c) Aluminum, gold, silver (d) Silver, aluminum, go

> An oversized yo-yo is made from two identical solid disks each of mass M = 2.00 kg and radius R = 10.0 cm. The two disks are joined by a solid cylinder of radius r = 4.00 cm and mass m = 1.00 kg as in Figure P8.40. Take the center of the cylinder as the

> A large grinding wheel in the shape of a solid cylinder of radius 0.330 m is free to rotate on a frictionless, vertical axle. A constant tangential force of 250. N applied to its edge causes the wheel to have an angular acceleration of 0.940 rad/s2. (a)

> If the system shown in Figure P8.37 is set in rotation about each of the axes mentioned in Problem 37, find the torque that will produce an angular acceleration of 1.50 rad/s2 in each case. Axes From Problem 37: (a) The x-axis, (b) The y-axis, and (c) A

> Four objects are held in position at the corners of a rectangle by light rods as shown in Figure P8.37. Find the moment of inertia of the system about (a) The x-axis, (b) The y-axis, and (c) An axis through O and perpendicular to the page. Figure P8.37:

> One end of a uniform 4.0-m-long rod of weight w is supported by a cable at an angle of θ = 37° with the rod. The other end rests against a wall, where it is held by friction. (See Fig. P8.36.) The coefficient of static friction be

> The large quadriceps muscle in the upper leg terminates at its lower end in a tendon attached to the upper end of the tibia (Fig. P8.35a). The forces on the lower leg when the leg is extended are modeled as in Figure P8.35b, where T( is the force of tens

> A 1200-N uniform boom at (( = 65° to the horizontal is supported by a cable at an angle θ = 25.0° to the horizontal as shown in Figure P8.34. The boom is pivoted at the bottom, and an object of weight w = 2000 N hangs f

> The chewing muscle, the masseter, is one of the strongest in the human body. It is attached to the mandible (lower jawbone) as shown in Figure P8.33a. The jawbone is pivoted about a socket just in front of the auditory canal. The forces acting on the jaw

> Write the necessary equations of equilibrium of the object shown in Figure P8.32. Take the origin of the torque equation about an axis perpendicular to the page through the point O. Figure P8.32:

> A refrigerator of width w and height h rests on a rough incline as in Figure P8.31. Find an expression for the maximum value θ can have before the refrigerator tips over. Note, the contact point between the refrigerator and incline shifts as

> You observe two helium balloons floating next to each other at the ends of strings secured to a table. The facing surfaces of the balloons are separated by 1–2 cm. You blow through the opening between the balloons. What happens to the balloons? (a) They

> A strut of length L = 3.00 m and mass m = 16.0 kg is held by a cable at an angle of θ = 30.0° with respect to the horizontal as shown in Figure P8.30. (a) Sketch a force diagram, indicating all the forces and their placement on th

> Figure P8.29 shows a uniform beam of mass m pivoted at its lower end, with a horizontal spring attached between its top end and a vertical wall. The beam makes an angle u with the horizontal. Find expressions for (a) The distance d the spring is stretche

> A hungry bear weighing 700. N walks out on a beam in an attempt to retrieve a basket of goodies hanging at the end of the beam (Fig. P8.28). The beam is uniform, weighs 200. N, and is 6.00 m long, and it is supported by a wire at an angle of Î&cedi

> A uniform plank of length 2.00 m and mass 30.0 kg is supported by three ropes, as indicated by the blue vectors in Figure P8.27. Find the tension in each rope when a 700.-N person is d = 0.500 m from the left end. Figure P8.27:

> A window washer is standing on a scaffold supported by a vertical rope at each end. The scaffold weighs 200 N and is 3.00 m long. What is the tension in each rope when the 700-N worker stands 1.00 m from one end?

> A 500.-N uniform rectangular sign 4.00 m wide and 3.00 m high is suspended from a horizontal, 6.00-m-long, uniform, 100.-N rod as indicated in Figure P8.25. The left end of the rod is supported by a hinge, and the right end is supported by a thin cable m

> When a person stands on tiptoe (a strenuous position), the position of the foot is as shown in Figure P8.24a. The total gravitational force on the body, F(g, is supported by the force n( exerted by the floor on the toes of one foot. A mechanical model of

> A person bending forward to lift a load “with his back” (Fig. P8.23a) rather than “with his knees” can be injured by large forces exerted on the muscles and vertebrae. The spine pivo

> A beam resting on two pivots has a length of L = 6.00 m and mass M = 90.0 kg. The pivot under the left end exerts a normal force n1 on the beam, and the second pivot placed a distance â„“ = 4.00 m from the left end exerts a normal force n

> In exercise physiology studies, it is sometimes important to determine the location of a person’s center of gravity. This can be done with the arrangement shown in Figure P8.21. A light plank rests on two scales that read Fg1 = 380. N a

> If global warming continues, it’s likely that some ice from the polar ice caps of the Earth will melt and the water will be distributed closer to the equator. If this occurs, would the length of the day (one rotation) (a) Increase, (b) Decrease, or (c) R

> A meter stick is found to balance at the 49.7-cm mark when placed on a fulcrum. When a 50.0-gram mass is attached at the 10.0-cm mark, the fulcrum must be moved to the 39.2-cm mark for balance. What is the mass of the meter stick?

> A cook holds a 2.00-kg carton of milk at arm’s length (Fig. P8.19). What force F(B must be exerted by the biceps muscle? (Ignore the weight of the forearm.) Figure P8.19:

> A uniform 35.0-kg beam of length (â„“ = 5.00 m is supported by a vertical rope located d = 1.20 m from its left end as in Figure P8.18. The right end of the beam is supported by a vertical column. Find (a) The tension in the rope and (b)

> 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 F(t in the deltoid muscle and the force F(s exerted by the shoulder on the humerus (upper-arm bone) to hold

> Spectators watch a bicycle stunt rider travel off the end of a 60.0° ramp, rise to the top of his trajectory and, at that instant, suddenly push his bike away from him so that he falls vertically straight down, reaching the ground 0.550 s later. How far

> A hiker inspects a tree frog sitting on a small stick in his hand. Suddenly startled, the hiker drops the stick from rest at a height of 1.85 m above the ground and, at the same instant, the frog leaps vertically upward, pushing the stick down so that it

> The Xanthar mothership locks onto an enemy cruiser with its tractor beam (Fig. P8.14); each ship is at rest in deep space with no propulsion following a devastating battle. The mothership is at x = 0 when its tractor beams are first engaged, a distance d

> A block of mass m = 1.50 kg is at rest on a ramp of mass M = 4.50 kg which, in turn, is at rest on a frictionless horizontal surface (Fig. P8.13a). The block and the ramp are aligned so that each has its center of mass located at x = 0. When released, th

> Find the x- and y -coordinates of the center of gravity for the boomerang in Figure P8.12a, modeling the boomerang as in Figure P8.12b, where each uniform leg of the model has a length of 0.300 m and a mass of 0.250 kg. (Note: Treat the legs like thin ro

> Find the x- and y-coordinates of the center of gravity of a 4.00-ft by 8.00-ft uniform sheet of plywood with the upper right quadrant removed as shown in Figure P8.11. Hint: The mass of any segment of the plywood sheet is proportional to the area of that

> A horizontal disk with moment of inertia I1 rotates with angular speed v1 about a vertical frictionless axle. A second horizontal disk having moment of inertia I2 drops onto the first, initially not rotating but sharing the same axis as the first disk. B

> Three solid, uniform boxes are aligned as in Figure P8.10. Find the x- and y-coordinates of the center of mass of the three boxes, measured from the bottom left corner of box A. Figure P8.10:

> Two bowling balls are at rest on top of a uniform wooden plank with their centers of mass located as in Figure P8.9. The plank has a mass of 5.00 kg and is 1.00 m long. Find the horizontal distance from the left end of the plank to the center of mass of

> Consider the following mass distribution, where x- and y-coordinates are given in meters: 5.0 kg at (0.0, 0.0) m, 3.0 kg at (0.0, 4.0) m, and 4.0 kg at (3.0, 0.0) m. Where should a fourth object of 8.0 kg be placed so that the center of mass of the four-

> A simple pendulum consists of a small object of mass 3.0 kg hanging at the end of a 2.0-m-long light string that is connected to a pivot point. (a) Calculate the magnitude of the torque (due to the force of gravity) about this pivot point when the string

> A dental bracket exerts a horizontal force of 80.0 N on a tooth at point B in Figure P8.6. What is the torque on the root of the tooth about point A? Figure P8.6:

> The density of air is 1.3 kg/m3 at sea level. From your knowledge of air pressure at ground level, estimate the height of the atmosphere. As a simplifying assumption, take the atmosphere to be of uniform density up to some height, after which the density

> Two point masses are the same distance R from an axis of rotation and have moments of inertia IA and IB. (a) If IB = 4IA, what is the ratio mB/mA of the two masses? (b) At what distance from the axis of rotation should mass A be placed so that IB = IA?

> Markings to indicate length are placed on a steel tape in a room that is at a temperature of 22°C. Measurements are then made with the same tape on a day when the temperature is 27°C. Are the measurements too long, too short, or accurate?

> A container filled with an ideal gas is connected to a reservoir of the same gas so that the number of moles in the container can change. If the pressure and volume of the container are each doubled while the temperature is held constant, what is the rat

> Calculate the net torque (magnitude and direction) on the beam in Figure P8.5 about (a) An axis through O perpendicular to the page and (b) An axis through C perpendicular to the page. Figure P8.5:

> A rubber balloon is blown up and the end tied. Is the pressure inside the balloon greater than, less than, or equal to the ambient atmospheric pressure? Explain.

> A sealed container contains a fixed volume of a monatomic ideal gas. If the gas temperature is increased by a factor of two, what is the ratio of the final to the initial (a) Pressure, (b) Average molecular kinetic energy, (c) Root-mean-square speed, and

> Suppose the volume of an ideal gas is doubled while the pressure is reduced by half. Does the internal energy of the gas increase, decrease, or remain the same? Explain.

> The air we breathe is largely composed of nitrogen (N2) and oxygen (O2) molecules. The mass of an N2 molecule is less than the mass of an O2 molecule. (a) For air at 300 K, is the average kinetic energy of an N2 molecule greater than, less than, or equal

> One of the predicted problems due to global warming is that ice in the polar ice caps will melt and raise sea levels everywhere in the world. Is that more of a worry for ice (a) At the North Pole, where most of the ice floats on water; (b) At the South P

> A mouse is initially at rest on a horizontal turntable mounted on a frictionless, vertical axle. As the mouse begins to walk clockwise around the perimeter, which of the following statements must be true of the turntable? (a) It also turns clockwise. (b)

> Once ski jumpers are airborne (Fig. CQ9.14), why do they bend their bodies forward and keep their hands at their sides? Figur CQ9.14:

> A cat usually lands on its feet regardless of the position from which it is dropped. A slow-motion film of a cat falling shows that the upper half of its body twists in one direction while the lower half twists in the opposite direction. (See Fig. CQ8.14

> Will an ice cube float higher in water or in an alcoholic beverage?

> Find the net torque on the wheel in Figure P8.4 about the axle through O perpendicular to the page, taking a = 10.0 cm and b = 25.0 cm. Figure P8.4:

> (a) Give an example in which the net force acting on an object is zero, yet the net torque is nonzero. (b) Give an example in which the net torque acting on an object is zero, yet the net force is nonzero.

> An ice cube is placed in a glass of water. What happens to the level of the water as the ice melts?

> An object is acted on by a single nonzero force of magnitude F. (a) Is it possible for the object to have zero acceleration (? (b) Is it possible for the object to have zero angular acceleration (? (c) Is it possible for the object to be in mechanical eq

> During inhalation, the pressure in the lungs is slightly less than external pressure and the muscles controlling exhalation are relaxed. Under water, the body equalizes internal and external pressures. Discuss the condition of the muscles if a person und

> If you toss a textbook into the air, rotating it each time about one of the three axes perpendicular to it, you will find that it will not rotate smoothly about one of those axes. (Try placing a strong rubber band around the book before the toss so that

> Many people believe that a vacuum created inside a vacuum cleaner causes particles of dirt to be drawn in. Actually, the dirt is pushed in. Explain.

> A person stands a distance R from a door’s hinges and pushes with a force F directed perpendicular to its surface. By what factor does the applied torque change if the person’s position and force change to (a) 2R and 2F, (b) 2R and F, (c) R and F/2, (d)

> Figure CQ9.4 shows aerial views from directly above two dams. Both dams are equally long (the vertical dimension in the diagram) and equally deep (into the page in the diagram). The dam on the left holds back a very large lake, while the dam on the right

> (a) Is it possible to calculate the torque acting on a rigid object without specifying an origin? (b) Is the torque independent of the location of the origin?

> A water tank open to the atmosphere at the top has two small holes punched in its side, one above the other. The holes are 5.00 cm and 12.0 cm above the floor. How high does water stand in the tank if the two streams of water hit the floor at the same pl

> The fishing pole in Figure P8.3 makes an angle of 20.0° with the horizontal. What is the magnitude of the torque exerted by the fish about an axis perpendicular to the page and passing through the angler’s hand if the fish pu

> Oil having a density of 930 kg/m3 floats on water. A rectangular block of wood 4.00 cm high and with a density of 960 kg/m3 floats partly in the oil and partly in the water. The oil completely covers the block. How far below the interface between the two

> In about 1657, Otto von Guericke, inventor of the air pump, evacuated a sphere made of two brass hemispheres (Fig. P9.89). Two teams of eight horses each could pull the hemispheres apart only on some trials and then “with greatest diffi

> A u-tube open at both ends is partially filled with water (Fig. P9.88a). Oil (p = 750 kg/m3) is then poured into the right arm and forms a column L = 5.00 cm high (Fig. P9.88b). (a) Determine the difference h in the heights of the two liquid surfaces. (b

> A light spring of constant k = 90.0 N/m is attached vertically to a table (Fig. P9.87a). A 2.00-g balloon is filled with helium (density = 0.179 kg/m3) to a volume of 5.00 m3 and is then connected to the spring, causing the spring to stretch as shown in

> A helium-filled balloon, whose envelope has a mass of 0.25 kg, is tied to a 2.0-m-long, 0.050-kg string. The balloon is spherical with a radius of 0.40 m. When released, it lifts a length h of the string and then remains in equilibrium, as in Figure P9.8

> Figure P9.85 shows a water tank with a valve. If the valve is opened, what is the maximum height attained by the stream of water coming out of the right side of the tank? Assume h = 10.0 m, L = 2.00 m, and θ = 30.0°, and that the

> A hydrometer is an instrument used to determine liquid density. A simple one is sketched in Figure P9.84. The bulb of a syringe is squeezed and released to lift a sample of the liquid of interest into a tube containing a calibrated rod of known density.

> The human brain and spinal cord are immersed in the cerebrospinal fluid. The fluid is normally continuous between the cranial and spinal cavities and exerts a pressure of 100 to 200 mm of H2O above the prevailing atmospheric pressure. In medical work, pr

> Superman attempts to drink water through a very long vertical straw as in Figure P9.82. With his great strength, he achieves maximum possible suction. The walls of the straw don’t collapse. (a) Find the maximum height through which he c

> The approximate diameter of the aorta is 0.50 cm; that of a capillary is 10. mm. The approximate average blood flow speed is 1.0 m/s in the aorta and 1.0 cm/s in the capillaries. If all the blood in the aorta eventually flows through the capillaries, est

> A worker applies a torque to a nut with a wrench 0.500 m long. Because of the cramped space, she must exert a force upward at an angle of 60.0° with respect to a line from the nut through the end of the wrench. If the force she exerts has magnitude 80.0

> Take the density of blood to be p and the distance between the feet and the heart to be hH. Ignore the flow of blood. (a) Show that the difference in blood pressure between the feet and the heart is given by PF - PH = pghH. (b) Take the density of blood

> In most species of clingfish (family Gobiesocidae), pelvic and pectoral fins converge to form a suction cup edged by hairy structures that allow a good seal even on rough surfaces. Experiments have shown that a clingfish’s suction cup can support up to 2

> Suppose two worlds, each having mass M and radius R, coalesce into a single world. Due to gravitational contraction, the combined world has a radius of only ¾ R. What is the average density of the combined world as a multiple of p0, the average density o

> An iron block of volume 0.20 m3 is suspended from a spring scale and immersed in a flask of water. Then the iron block is removed, and an aluminum block of the same volume replaces it. (a) In which case is the buoyant force the greatest, for the iron blo

> The total cross-sectional area of the load-bearing calcified portion of the two forearm bones (radius and ulna) is approximately 2.4 cm2. During a car crash, the forearm is slammed against the dashboard. The arm comes to rest from an initial speed of 80

> Determine the elongation of the rod in Figure P9.75 if it is under a tension of 5.8 x 103 N. Figure P9.75:

> The deepest point in the ocean is in the Mariana Trench, about 11 km deep. The pressure at the ocean floor is huge, about 1.13 x 108 N/m2. (a) Calculate the change in volume of 1.00 m3 of water carried from the surface to the bottom of the Pacific. (b) T

> A high-speed lifting mechanism supports an 800. -kg object with a steel cable that is 25.0 m long and 4.00 cm2 in cross-sectional area. (a) Determine the elongation of the cable. (b) By what additional amount does the cable increase in length if the obje

> A stainless-steel orthodontic wire is applied to a tooth, as in Figure P9.72. The wire has an unstretched length of 3.1 cm and a radius of 0.11 mm. If the wire is stretched 0.10 mm, find the magnitude and direction of the force on the tooth. Disregard th

> Bone has a Young’s modulus of 18 x 109 Pa. Under compression, it can withstand a stress of about 160 x 106 Pa before breaking. Assume that a femur (thigh bone) is 0.50 m long, and calculate the amount of compression this bone can withstand before breakin

> A man opens a 1.00-m wide door by pushing on it with a force of 50.0 N directed perpendicular to its surface. What magnitude of torque does he apply about an axis through the hinges if the force is applied (a) At the center of the door? (b) At the edge f

> Two spheres, one hollow and one solid, are rotating with the same angular speed around an axis through their centers. Both spheres have the same mass and radius. Which sphere, if either, has the higher rotational kinetic energy? (a) The hollow sphere. (b

> Assume that if the shear stress in steel exceeds about 4.00 x 108 N/m2, the steel ruptures. Determine the shearing force necessary to (a) Shear a steel bolt 1.00 cm in diameter and (b) Punch a 1.00-cm-diameter hole in a steel plate 0.500 cm thick.

> For safety in climbing, a mountaineer uses a nylon rope that is 50. m long and 1.0 cm in diameter. When supporting a 90. -kg climber, the rope elongates 1.6 m. Find its Young’s modulus.

> Artificial diamonds can be made using high-pressure, high-temperature presses. Suppose an artificial diamond of volume 1.00 x 10-6 m3 is formed under a pressure of 5.00 GPa. Find the change in its volume when it is released from the press and brought to

> A plank 2.00 cm thick and 15.0 cm wide is firmly attached to the railing of a ship by clamps so that the rest of the board extends 2.00 m horizontally over the sea below. A man of mass 80.0 kg is forced to stand on the very end. If the end of the board d

> A 25.0-m long steel cable with a cross-sectional area of 2.03 x 10-3 m2 is used to suspend a 3.50 x 103 -kg container. By how much will the cable stretch once bearing the load?

> A 200.- kg load is hung on a wire of length 4.00 m, cross-sectional area 0.200 x 10–4 m2, and Young’s modulus 8.00 x 1010 N/m2. What is its increase in length?

> Small spheres of diameter 1.00 mm fall through 20°C water with a terminal speed of 1.10 cm/s. Calculate the density of the spheres.

> The viscous force on an oil drop is measured to be equal to 3.0 x 10-13 N when the drop is falling through air with a speed of 4.5 x 10-4 m/s. If the radius of the drop is 2.5 x 10-6 m, what is the viscosity of air?

> Glycerin in water diffuses along a horizontal column that has a cross-sectional area of 2.0 cm2. The concentration gradient is 3.0 x 10-2 kg/m4, and the diffusion rate is found to be 5.7 x 10-15 kg/s. Determine the diffusion coefficient.