Physics for Scientists and Engineers with Modern Physics
4th Edition
ISBN: 9780131495081
Author: Douglas C. Giancoli
Publisher: Addison-Wesley
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Textbook Question
Chapter 12, Problem 12P
(II) Find the tension in the two wires supporting the traffic light shown in Fig. 12–52.
FIGURE 12–52
Problem 12.
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(II) The Achilles tendon is attached to the rear of the foot
as shown in Fig. 9–73. When a person elevates himself just
barely off the floor on the “ball of one foot," estimate the
tension Fr in the Achilles tendon (pulling upward), and
the (downward) force Fg exerted by the lower leg bone on
the foot. Assume the person has a mass of 72 kg and D is
twice as long as d.
- Leg bone
Achilles
tendon
Ball of foot
(pivot point)
FB
FIGURE 9–73
Problem 36.
(II) A 110-kg horizontal beam is supported at each end.A 320-kg piano rests a quarter of the way from one end.What is the vertical force on each of the supports?
In a mountain-climbing technique called the "Tyrolean tra-
verse," a rope is anchored on both ends (to rocks or strong
trees) across a deep chasm, and then a climber traverses the
rope while attached by a sling as in Fig. 9–91. This technique
generates tremendous forces in the rope and anchors, so a
basic understanding of physics is crucial for safety. A typical
climbing rope can undergo a tension force of perhaps 29 kN
before breaking, and a “safety factor" of 10 is usually recom-
mended. The length of rope used in the Tyrolean traverse
must allow for some “sag" to remain in the recommended
safety range. Consider a 75-kg climber at the center of a
Tyrolean traverse, spanning a 25-m chasm. (a) To be within its
recommended safety range, what minimum distance x must
the rope sag? (b) If the Tyrolean traverse is set up incorrectly
so that the rope sags by only one-fourth the distance found in
(a), determine the tension in the rope. Ignore stretching of
the rope. Will the rope break?
25 m…
Chapter 12 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 12.1 - For simplicity, we wrote the equation in Example...Ch. 12.2 - We did not need to use the force equation to solve...Ch. 12.2 - CHAPTER-OPENING QUESTIONGuess Now! The diving...Ch. 12.2 - Why is it reasonable to ignore friction along the...Ch. 12.4 - Two steel wires have the same length and are under...Ch. 12 - Describe several situations in which an object is...Ch. 12 - A bungee jumper momentarily comes to rest at the...Ch. 12 - Prob. 3QCh. 12 - Your doctors scale has arms on which weights slide...Ch. 12 - A ground retaining wall is shown in Fig. 1240a....
Ch. 12 - Can the sum of the torques on an object be zero...Ch. 12 - A ladder, leaning against a wall, makes a 60 angle...Ch. 12 - A uniform meter stick supported at the 25-cm mark...Ch. 12 - Prob. 9QCh. 12 - Prob. 10QCh. 12 - Place yourself facing the edge of an open door....Ch. 12 - Prob. 12QCh. 12 - Prob. 13QCh. 12 - Which of the configurations of brick, (a) or (b)...Ch. 12 - Name the type of equilibrium for each position of...Ch. 12 - Is the Youngs modulus for a bungee cord smaller or...Ch. 12 - Examine how a pair of scissors or shears cuts...Ch. 12 - Materials such as ordinary concrete and stone are...Ch. 12 - (I) Three forces are applied to a tree sapling, as...Ch. 12 - (I) Approximately what magnitude force, FM, must...Ch. 12 - Prob. 3PCh. 12 - (I) A tower crane (Fig. 1248a) must always be...Ch. 12 - (II) Calculate the forces FA and FB that the...Ch. 12 - Prob. 6PCh. 12 - (II) The two trees in Fig. 1250 are 6.6 m apart. A...Ch. 12 - Prob. 8PCh. 12 - Prob. 9PCh. 12 - Prob. 10PCh. 12 - (II) Find the tension in the two cords shown in...Ch. 12 - (II) Find the tension in the two wires supporting...Ch. 12 - Prob. 13PCh. 12 - (II) The force required to pull the cork out of...Ch. 12 - (II) Calculate and FA and FB for the beam shown in...Ch. 12 - Prob. 16PCh. 12 - Prob. 17PCh. 12 - (II) Three children are trying to balance on a...Ch. 12 - (II) The Achilles tendon is attached to the rear...Ch. 12 - (II) A shop sign weighing 215 N is supported by a...Ch. 12 - (II) A traffic light hangs from a pole as shown in...Ch. 12 - (II) A uniform steel beam has a mass of 940 kg. On...Ch. 12 - (II) Two wires run from the top of a pole 2.6 m...Ch. 12 - (II) A large 62.0-kg board is propped at a 45...Ch. 12 - (II) Repeat Problem 24 assuming the coefficient of...Ch. 12 - (II) A 0.75-kg sheet hangs from a massless...Ch. 12 - (II) A uniform rod AB of length 5.0 m and mass M =...Ch. 12 - (III) A 56.0-kg person stands 2.0 m from the...Ch. 12 - (III) A door 2.30 m high and 1.30 m wide has a...Ch. 12 - (III) A cubic crate of side s = 2.0 m is...Ch. 12 - (III) A refrigerator is approximately a uniform...Ch. 12 - (III) A uniform ladder of mass m and length leans...Ch. 12 - Prob. 33PCh. 12 - (I) A nylon string on a tennis racket is under a...Ch. 12 - (I) A marble column of cross-sectional area 1.4 m2...Ch. 12 - (I) By how much is the column in Problem 35...Ch. 12 - (I) A sign (mass 1700 kg) hangs from the end of a...Ch. 12 - (II) How much pressure is needed to compress the...Ch. 12 - Prob. 39PCh. 12 - (II) At depths of 2000 m in the sea, the pressure...Ch. 12 - (III) A pole projects horizontally from the front...Ch. 12 - (I) The femur bone in the human leg has a minimum...Ch. 12 - (II) (a) What is the maximum tension possible in a...Ch. 12 - (II) If a compressive force of 3.3 104 N is...Ch. 12 - (II) (a) What is the minimum cross-sectional area...Ch. 12 - (II) Assume the supports of the uniform cantilever...Ch. 12 - (II) An iron bolt is used to connect two iron...Ch. 12 - (II) A steel cable is to support an elevator whose...Ch. 12 - (II) A heavy load Mg = 66.0 kN hangs at point E of...Ch. 12 - (II) Figure 1271 shows a simple truss that carries...Ch. 12 - (II) (a) What minimum cross-sectional area must...Ch. 12 - (II) onsider again Example 1211 but this time...Ch. 12 - (III) The truss shown in Fig. 1272 supports a...Ch. 12 - (III) Suppose in Example 1211, a 23-ton truck (m =...Ch. 12 - (III) For the Pratt truss shown in Fig. 1273,...Ch. 12 - (II) How high must a pointed arch be if it is to...Ch. 12 - The mobile in Fig. 1274 is in equilibrium. Object...Ch. 12 - A tightly stretched high wire is 36 m long. It...Ch. 12 - What minimum horizontal force F is needed to pull...Ch. 12 - A 28-kg round table is supported by three legs...Ch. 12 - When a wood shelf of mass 6.6 kg is fastened...Ch. 12 - Prob. 62GPCh. 12 - The center of gravity of a loaded truck depends on...Ch. 12 - In Fig. 1279, consider the right-hand...Ch. 12 - Assume that a single-span suspension bridge such...Ch. 12 - When a mass of 25 kg is hung from the middle of a...Ch. 12 - The forces acting on a 77,000-kg aircraft flying...Ch. 12 - A uniform flexible steel cable of weight mg is...Ch. 12 - A 20.0-m-long uniform beam weighing 650 N rests on...Ch. 12 - A cube of side l rests on a rough floor. It is...Ch. 12 - A 65.0-kg painter is on a uniform 25-kg scaffold...Ch. 12 - A man doing push-ups pauses in the position shown...Ch. 12 - A 23-kg sphere rests between two smooth planes as...Ch. 12 - A 15.0-kg ball is supported from the ceiling by...Ch. 12 - Parachutists whose chutes have failed to open have...Ch. 12 - A steel wire 2.3 mm in diameter stretches by...Ch. 12 - A 2500-kg trailer is attached to a stationary...Ch. 12 - Prob. 78GPCh. 12 - A 25-kg object is being lifted by pulling on the...Ch. 12 - A uniform 6.0-m-long ladder of mass 16.0 kg leans...Ch. 12 - There is a maximum height of a uniform vertical...Ch. 12 - A 95,000-kg train locomotive starts across a...Ch. 12 - A 23.0-kg backpack is suspended midway between two...Ch. 12 - A uniform beam of mass M and length l is mounted...Ch. 12 - Two identical, uniform beams are symmetrically set...Ch. 12 - If 35 kg is the maximum mass m that a person can...Ch. 12 - (a) Estimate the magnitude of the force FM the...Ch. 12 - One rod of the square frame shown in Fig. 1295...Ch. 12 - A steel rod of radius R = 15 cm and length 0,...Ch. 12 - A home mechanic wants to raise the 280-kg engine...Ch. 12 - A 2.0-m-high box with a 1.0-m-squarc base is moved...Ch. 12 - You are on a pirate ship and being forced to walk...Ch. 12 - A uniform sphere of weight mg and radius r0 is...Ch. 12 - Use the method of joints to determine the force in...Ch. 12 - A uniform ladder of mass m and length leans at an...Ch. 12 - In a mountain-climbing technique called the...Ch. 12 - (III) A metal cylinder has an original diameter of...Ch. 12 - (III) Two springs, attached by a rope, are...
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- A 23.0-kg backpack is suspended midway between two trees by a light cord as in Fig. 9–51. A bear grabs the backpack and pulls vertically downward with a constant force, so that each section of cord makes an angle of 27° belowthe horizontal. Initially, without the bear pulling, the angle was 15°; the tension in the cord with the bear pulling is double what it was when he was not. Calculate the force the bear is exerting on the backpack.arrow_forward(II) A 2500-kg trailer is attached to a stationary truck at point B, Fig. 9–61. Determine the normal force exerted by the road on the rear tires at A, and the vertical force exerted on the trailer by the support B. B Mg 2.5 m 5.5 m FIGURE 9-61 Problem 21.arrow_forward(II) Find the tension in the two cords shown in Fig. 9-45. Neglect the mass of the cords, and assume 9. that the angle e is 33° and the mass m is 170 kg. FIGURE 9-45 Problem 11.arrow_forward
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- (III) A door 2.30 m high and 1.30 m wide has a mass of 13.0 kg. A hinge 0.40 m from the top and another hinge 0.40 m from the bottom each support half the door's weight (Fig. 9–69). Assume that the center of gravity is at the geometrical center of the door, and determine 40 cm 2.30 m the horizontal and vertical force components exerted by each hinge on the door. -1.30 m- F40 cm FIGURE 9-69 Problem 29.arrow_forward(II) Two cords support a chandelier in the manner shownin Fig. 9–4 except that the upper cord makes an angle of45° with the ceiling. If the cords can sustain a force of1660 N without breaking, what is the maximum chandelierweight that can be supported?arrow_forward17-45. The drop gate at the end of the trailer has a mass of 1.25 Mg and mass center at G. If it is supported by the cable AB and hinge at C, determine the tension in the cable when the truck begins to accelerate at 5 m/s?. Also, what are the horizontal and vertical components of reaction at the hinge C? 30 1.5 m 45°arrow_forward
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