Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN: 9781133939146
Author: Katz, Debora M.
Publisher: Cengage Learning
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Chapter 14, Problem 75PQ
Ruby, with mass 55.0 kg, is trying to reach a box on a high shelf by standing on her tiptoes. In this position, half her weight is supported by the normal force exerted by the floor on the toes of each foot as shown in Figure P14.75A. This situation can be modeled mechanically by representing the force on Ruby’s Achilles tendon with
FIGURE P14.75
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Chapter 14 Solutions
Physics for Scientists and Engineers: Foundations and Connections
Ch. 14.1 - A rubber duck floats in a bathtub. Imagine moving...Ch. 14.1 - Prob. 14.2CECh. 14.2 - CASE STUDY Hanging a Plane from a Single Point In...Ch. 14.2 - Prob. 14.4CECh. 14.4 - Imagine two vertical rods initially of equal...Ch. 14 - What Is Static Equilibrium? Problems 13 are...Ch. 14 - Prob. 2PQCh. 14 - Two identical balls are attached to a...Ch. 14 - While working on homework together, your friend...Ch. 14 - Consider the sketch of a portion of a...
Ch. 14 - Prob. 6PQCh. 14 - Prob. 7PQCh. 14 - Prob. 8PQCh. 14 - The keystone of an arch is the stone at the top...Ch. 14 - Prob. 10PQCh. 14 - Stand straight and comfortably with your feet...Ch. 14 - Prob. 12PQCh. 14 - Prob. 13PQCh. 14 - Prob. 14PQCh. 14 - Prob. 15PQCh. 14 - Prob. 16PQCh. 14 - Prob. 17PQCh. 14 - Prob. 18PQCh. 14 - Prob. 19PQCh. 14 - Prob. 20PQCh. 14 - Prob. 21PQCh. 14 - The inner planets of our solar system are...Ch. 14 - Two Boy Scouts, Bobby and Jimmy, are carrying a...Ch. 14 - Prob. 24PQCh. 14 - A painter of mass 87.8 kg is 1.45 m from the top...Ch. 14 - Consider the situation in Problem 25. Tests have...Ch. 14 - Children playing pirates have suspended a uniform...Ch. 14 - Prob. 28PQCh. 14 - Prob. 29PQCh. 14 - A 5.45-N beam of uniform density is 1.60 m long....Ch. 14 - A wooden door 2.1 m high and 0.90 m wide is hung...Ch. 14 - A 215-kg robotic arm at an assembly plant is...Ch. 14 - Problems 33 and 34 are paired. One end of a...Ch. 14 - For the uniform beam in Problem 33, find the...Ch. 14 - Prob. 35PQCh. 14 - A square plate with sides of length 4.0 m can...Ch. 14 - Prob. 37PQCh. 14 - At a museum, a 1300-kg model aircraft is hung from...Ch. 14 - A uniform wire (Y = 2.0 1011 N/m2) is subjected...Ch. 14 - A brass wire and a steel wire, both of the same...Ch. 14 - In Example 14.3, we found that one of the steel...Ch. 14 - A carbon nanotube is a nanometer-scale cylindrical...Ch. 14 - A nanotube with a Youngs modulus of 1.000 1012 Pa...Ch. 14 - Consider a nanotube with a Youngs modulus of 2.130...Ch. 14 - Prob. 45PQCh. 14 - Use the graph in Figure P14.46 to list the three...Ch. 14 - Prob. 47PQCh. 14 - A company is testing a new material made of...Ch. 14 - Prob. 49PQCh. 14 - Prob. 50PQCh. 14 - Prob. 51PQCh. 14 - Prob. 52PQCh. 14 - Prob. 53PQCh. 14 - Prob. 54PQCh. 14 - Prob. 55PQCh. 14 - Prob. 56PQCh. 14 - A copper rod with length 1.4 m and cross-sectional...Ch. 14 - Prob. 58PQCh. 14 - Prob. 59PQCh. 14 - Bruce Lee was famous for breaking concrete blocks...Ch. 14 - Prob. 61PQCh. 14 - Prob. 62PQCh. 14 - Prob. 63PQCh. 14 - A One end of a metal rod of weight Fg and length L...Ch. 14 - Prob. 65PQCh. 14 - A steel cable 2.00 m in length and with...Ch. 14 - Prob. 67PQCh. 14 - Prob. 68PQCh. 14 - Prob. 69PQCh. 14 - Prob. 70PQCh. 14 - Prob. 71PQCh. 14 - Prob. 72PQCh. 14 - Prob. 73PQCh. 14 - We know from studying friction forces that static...Ch. 14 - Ruby, with mass 55.0 kg, is trying to reach a box...Ch. 14 - An object is being weighed using an unequal-arm...Ch. 14 - Prob. 77PQCh. 14 - A massless, horizontal beam of length L and a...Ch. 14 - A rod of length 4.00 m with negligible mass is...Ch. 14 - A rod of length 4.00 m with negligible mass is...Ch. 14 - A horizontal, rigid bar of negligible weight is...Ch. 14 - Prob. 82PQCh. 14 - Prob. 83PQCh. 14 - Prob. 84PQCh. 14 - Prob. 85PQ
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- A massless, horizontal beam of length L and a massless rope support a sign of mass m (Fig. P14.78). a. What is the tension in the rope? b. In terms of m, g, d, L, and , what are the components of the force exerted by the beam on the wall? FIGURE P14.78arrow_forwardA 215-kg robotic arm at an assembly plant is extended horizontally (Fig. P14.32). The massless support rope attached at point B makes an angle of 15.0 with the horizontal, and the center of mass of the arm is at point C. a. What is the tension in the support rope? b. What are the magnitude and direction of the force exerted by the hinge A on the robotic arm to keep the arm in the horizontal position? FIGURE P14.32arrow_forwardWhy is the following situation impossible? A worker in a factory pulls a cabinet across the floor using a rope as shown in Figure P12.36a. The rope make an angle = 37.0 with the floor and is tied h1 = 10.0 cm from the bottom of the cabinet. The uniform rectangular cabinet has height = 100 cm and width w = 60.0 cm, and it weighs 400 N. The cabinet slides with constant speed when a force F = 300 N is applied through the rope. The worker tires of walking backward. He fastens the rope to a point on the cabinet h2 = 65.0 cm off the floor and lays the rope over his shoulder so that he can walk forward and pull as shown in Figure P12.36b. In this way, the rope again makes an angle of = 37.0 with the horizontal and again has a tension of 300 N. Using this technique, the worker is able to slide the cabinet over a long distance on the floor without tiring. Figure P12.36 Problems 36 and 44.arrow_forward
- Why is the following situation impossible? A uniform beam of mass mk = 3.00 kg and length = 1.00 m supports blocks with masses m1 = 5.00 kg and m2 = 15.0 kg at two positions as shown in Figure P12.2. The beam rests on two triangular blocks, with point P a distance d = 0.300 m to the right of the center of gravity of the beam. The position of the object of mass m2 is adjusted along the length of the beam until the normal force on the beam at O is zero. Figure P12.2arrow_forwardA uniform beam of length 7.60 m and weight 4.50 102 N is carried by two workers, Sam and Joe, as shown in Figure P12.6. Determine the force that each person exerts on the beam. Figure P12.6arrow_forwardA stepladder of negligible weight is constructed as shown in Figure P12.40, with AC = BC = . A painter of mass m stands on the ladder a distance d from the bottom. Assuming the floor is frictionless, find (a) the tension in the horizontal bar DE connecting the two halves of the ladder, (b) the normal forces at A and B, and (c) the components of the reaction force at the single hinge C that the left half of the ladder exerts on the right half. Suggestion: Treat the ladder as a single object, but also treat each half of the ladder separately. Figure P12.40 Problems 40 and 41.arrow_forward
- A rod of length 4.00 m with negligible mass is hinged to a wall. A rope attached to the end of the rod runs up to the wall at an angle of exactly 45, helping support the rod, while a sign of weight 10.0 N is hanging by two ropes attached to the bottom of the rod. The ropes make an angle of exactly 30 with the rod as shown in Figure P14.79. Another sign with a weight of 10.0 N is attached to the top of the rod with its center of mass at the midpoint of the rod. The entire system is in equilibrium. Find the magnitude of the tension in the rope above the rod that is also attached to the wall. FIGURE P14.79 Problems 79 and 80.arrow_forwardA horizontal, rigid bar of negligible weight is fixed against a vertical wall at one end and supported by a vertical string at the other end. The bar has a length of 50.0 cm and is used to support a hanging block of weight 400.0 N from a point 30.0 cm from the wall as shown in Figure P14.81. The string is made from a material with a tensile strength of 1.2 108 N/m2. Determine the largest diameter of the string for which it would still break. FIGURE P14.81arrow_forwardChildren playing pirates have suspended a uniform wooden plank with mass 15.0 kg and length 2.50 m as shown in Figure P14.27. What is the tension in each of the three ropes when Sophia, with a mass of 23.0 kg, is made to walk the plank and is 1.50 m from reaching the end of the plank? FIGURE P14.27arrow_forward
- At a museum, a 1300-kg model aircraft is hung from a lightweight beam of length 12.0 m that is free to pivot about its base and is supported by a massless cable (Fig. P14.38). Ignore the mass of the beam. a. What is the tension in the section of the cable between the beam and the wall? b. What are the horizontal and vertical forces that the pivot exerts on the beam? FIGURE P14.38 (a) From the free-body diagram, the angle that the string tension makes with the beam is = 55.0 + 18.0 = 73.0, and the perpendicular component of the string tension is FT sin73.0. Summing torques around the base of the rod gives (Eq. 14.2): =0:(12.0m)(1300kg)(9.81m/s2)cos55.0+FT(12.0m)sin73.0=0FT=(12.0m)(1300kg)(9.81m/s2)cos55.0(12.0m)sin73.0FT=7.65103N Figure P14.38ANS (b) Using force balance (Eq. 14.1): Fx=0:FHFTcos18.0=0FH=FTcos18.0=[(12.0m)(1300kg)(9.81m/s2)cos55.0(12.0m)sin73.0]cos18.0=7.27103NFy=0:FVFTsin18.0(1300kg)(9.81m/s2)=0 FV=FTsin18.0+(1300kg)gFV=[(12.0m)(1300kg)(9.81m/s2)cos55.0(12.0m)sin73.0]sin18.0+(1300kg)(9.81m/s2)FV=1.51104Narrow_forwardConsider a nanotube with a Youngs modulus of 2.130 1012 N/m2 that experiences a tensile stress of 5.3 1010 N/m2. Steel has a Youngs modulus of about 2.000 1011 Pa. How much stress would cause a piece of steel to experience the same strain as the nanotube?arrow_forwardA stepladder of negligible weight is constructed as shown in Figure P12.40, with AC = BC = = 4.00 m. A painter of mass m = 70.0 kg stands on the ladder d = 3.00 m from the bottom. Assuming the floor is frictionless, find (a) the tension in the horizontal bar DE connecting the two halves of the ladder, (b) the normal forces at A and B, and (c) the components of the reaction force at the single hinge C that the left half of the ladder exerts on the right half. Suggestion: Treat the ladder as a single object, but also treat each half of the ladder separately. Figure P12.40 Problems 40 and 41.arrow_forward
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