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Solution Manual - Engineering Mechanics Statics 12th Edition By R.C.Hibbeler ch5

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### my Statics ch5

1. 1. 5 Solutions 44918 1/23/09 5:11 PM Page 320 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–1. Draw the free-body diagram of the 50-kg paper roll which has a center of mass at G and rests on the smooth blade of the paper hauler. Explain the significance of each force acting on the diagram. (See Fig. 5–7b.) 35 mm G B A 30Њ 5–2. Draw the free-body diagram of member AB, which is 390 lb supported by a roller at A and a pin at B. Explain the significance of each force on the diagram. (See Fig. 5–7b.) 13 12 800 lb и ft 5 A 8 ft 4 ft 3 ft 30Њ B 320
2. 2. 5 Solutions 44918 1/23/09 5:11 PM Page 321 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–3. Draw the free-body diagram of the dumpster D of the truck, which has a weight of 5000 lb and a center of gravity at G. It is supported by a pin at A and a pin-connected hydraulic cylinder BC (short link). Explain the significance of each force on the diagram. (See Fig. 5–7b.) G 1.5 m D 1m 3m B A 30Њ C 20Њ *5–4. Draw the free-body diagram of the beam which supports the 80-kg load and is supported by the pin at A and D a cable which wraps around the pulley at D. Explain the significance of each force on the diagram. (See Fig. 5–7b.) 5 4 3 A B E C 2m 2m 1.5 m 321
3. 3. 5 Solutions 44918 1/23/09 5:11 PM Page 322 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–5. Draw the free-body diagram of the truss that is B supported by the cable AB and pin C. Explain the significance of each force acting on the diagram. (See Fig. 5–7b.) 30Њ A 2m C 3 kN 4 kN 2m 2m 2m 5–6. Draw the free-body diagram of the crane boom AB which has a weight of 650 lb and center of gravity at G. The 12 ft boom is supported by a pin at A and cable BC. The load of B 1250 lb is suspended from a cable attached at B. Explain the significance of each force acting on the diagram. (See 18 ft 13 Fig. 5–7b.) 5 12 G C 30Њ A 322
4. 4. 5 Solutions 44918 1/23/09 5:11 PM Page 323 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–7. Draw the free-body diagram of the “spanner 20 lb wrench” subjected to the 20-lb force. The support at A can A be considered a pin, and the surface of contact at B is smooth. Explain the significance of each force on the diagram. (See Fig. 5–7b.) 1 in. B 6 in. *5–8. Draw the free-body diagram of member ABC which D C is supported by a smooth collar at A, roller at B, and short 2.5 kN link CD. Explain the significance of each force acting on the diagram. (See Fig. 5–7b.) 3m 60Њ 4 kN и m A B 45Њ 4m 6m 323
5. 5. 5 Solutions 44918 1/23/09 5:11 PM Page 324 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–9. Draw the free-body diagram of the bar, which has a 3 in. negligible thickness and smooth points of contact at A, B, 30Њ and C. Explain the significance of each force on the 5 in. diagram. (See Fig. 5–7b.) C B A 8 in. 10 lb 30Њ 324
6. 6. 5 Solutions 44918 1/23/09 5:11 PM Page 325 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–10. Draw the free-body diagram of the winch, which B 3 in. consists of a drum of radius 4 in. It is pin-connected at its center C, and at its outer rim is a ratchet gear having a mean A 2 in. radius of 6 in. The pawl AB serves as a two-force member (short link) and prevents the drum from rotating. Explain 6 in. the significance of each force on the diagram. (See Fig. 5–7b.) C 4 in. 500 lb 5–11. Determine the normal reactions at A and B in Prob. 5–1. 325
7. 7. 5 Solutions 44918 1/23/09 5:11 PM Page 326 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–12. Determine the tension in the cord and the horizontal and vertical components of reaction at support A of the beam in Prob. 5–4. •5–13. Determine the horizontal and vertical components of reaction at C and the tension in the cable AB for the truss in Prob. 5–5. 326
8. 8. 5 Solutions 44918 1/23/09 5:11 PM Page 327 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–14. Determine the horizontal and vertical components of reaction at A and the tension in cable BC on the boom in Prob. 5–6. 5–15. Determine the horizontal and vertical components of reaction at A and the normal reaction at B on the spanner wrench in Prob. 5–7. *5–16. Determine the normal reactions at A and B and the force in link CD acting on the member in Prob. 5–8. 327
9. 9. 5 Solutions 44918 1/23/09 5:11 PM Page 328 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–17. Determine the normal reactions at the points of contact at A, B, and C of the bar in Prob. 5–9. 5–18. Determine the horizontal and vertical components of reaction at pin C and the force in the pawl of the winch in Prob. 5–10. 328
10. 10. 5 Solutions 44918 1/23/09 5:11 PM Page 329 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–19. Compare the force exerted on the toe and heel of a 120 lb 120-lb woman when she is wearing regular shoes and 120 lb stiletto heels. Assume all her weight is placed on one foot and the reactions occur at points A and B as shown. A B A B 5.75 in. 1.25 in. 0.75 in. 3.75 in. 329
11. 11. 5 Solutions 44918 1/23/09 5:11 PM Page 330 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–20. The train car has a weight of 24 000 lb and a center of gravity at G. It is suspended from its front and rear on the track by six tires located at A, B, and C. Determine the normal reactions on these tires if the track is assumed to be a smooth surface and an equal portion of the load is G supported at both the front and rear tires. C 6 ft 4 ft B A 5 ft 330
12. 12. 5 Solutions 44918 1/23/09 5:11 PM Page 331 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–21. Determine the horizontal and vertical components 60 kN of reaction at the pin A and the tension developed in cable BC used to support the steel frame. 1m 1m 1m B 30 kN и m 3m 5 4 3 C A 331
13. 13. 5 Solutions 44918 1/23/09 5:11 PM Page 332 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–22. The articulated crane boom has a weight of 125 lb and 4 ft center of gravity at G. If it supports a load of 600 lb, determine A 1 ft G the force acting at the pin A and the force in the hydraulic cylinder BC when the boom is in the position shown. B 8 ft 1 ft 40Њ C 332
14. 14. 5 Solutions 44918 1/23/09 5:11 PM Page 333 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–23. The airstroke actuator at D is used to apply a force of F = 200 N on the member at B. Determine the horizontal and vertical components of reaction at the pin A and the C force of the smooth shaft at C on the member. 15Њ 600 mm B A 60Њ D 600 mm F 200 mm 333
15. 15. 5 Solutions 44918 1/23/09 5:11 PM Page 334 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–24. The airstroke actuator at D is used to apply a force of F on the member at B. The normal reaction of the smooth shaft at C on the member is 300 N. Determine the C magnitude of F and the horizontal and vertical components of reaction at pin A. 15Њ 600 mm B A 60Њ D 600 mm F 200 mm 334
16. 16. 5 Solutions 44918 1/23/09 5:11 PM Page 335 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–25. The 300-lb electrical transformer with center of gravity at G is supported by a pin at A and a smooth pad at B. 1.5 ft Determine the horizontal and vertical components of reaction at the pin A and the reaction of the pad B on the transformer. A 3 ft G B 335
17. 17. 5 Solutions 44918 1/23/09 5:11 PM Page 336 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–26. A skeletal diagram of a hand holding a load is shown in the upper figure. If the load and the forearm have masses D of 2 kg and 1.2 kg, respectively, and their centers of mass are located at G1 and G2, determine the force developed in the biceps CD and the horizontal and vertical components of reaction at the elbow joint B. The forearm supporting system can be modeled as the structural system shown in G1 the lower figure. C B A G2 D G1 75Њ C B A G2 100 mm 135 mm 65 mm 336
18. 18. 5 Solutions 44918 1/23/09 5:11 PM Page 337 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–27. As an airplane’s brakes are applied, the nose wheel exerts two forces on the end of the landing gear as shown. Determine the horizontal and vertical components of C B 30Њ reaction at the pin C and the force in strut AB. 400 mm 20Њ A 600 mm 2 kN 6 kN 337
19. 19. 5 Solutions 44918 1/23/09 5:11 PM Page 338 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–28. The 1.4-Mg drainpipe is held in the tines of the fork lift. Determine the normal forces at A and B as functions of the blade angle u and plot the results of force (vertical axis) 0.4 m versus u (horizontal axis) for 0 … u … 90°. A B u 338
20. 20. 5 Solutions 44918 1/23/09 5:11 PM Page 339 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–29. The mass of 700 kg is suspended from a trolley d which moves along the crane rail from d = 1.7 m to A d = 3.5 m. Determine the force along the pin-connected knee strut BC (short link) and the magnitude of force at pin C A as a function of position d. Plot these results of F and F BC A (vertical axis) versus d (horizontal axis). 2m B 1.5 m 339
21. 21. 5 Solutions 44918 1/23/09 5:11 PM Page 340 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–30. If the force of F = 100 lb is applied to the handle of C the bar bender, determine the horizontal and vertical components of reaction at pin A and the reaction of the roller B on the smooth bar. 40 in. F 60Њ B A 5 in. 340
22. 22. 5 Solutions 44918 1/23/09 5:11 PM Page 341 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–31. If the force of the smooth roller at B on the bar C bender is required to be 1.5 kip, determine the horizontal and vertical components of reaction at pin A and the required magnitude of force F applied to the handle. 40 in. F 60Њ B A 5 in. 341
23. 23. 5 Solutions 44918 1/23/09 5:11 PM Page 342 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–32. The jib crane is supported by a pin at C and rod AB. 4m If the load has a mass of 2 Mg with its center of mass located A at G, determine the horizontal and vertical components of reaction at the pin C and the force developed in rod AB on the crane when x = 5 m. 3.2 m 0.2 m B C G D x 342
24. 24. 5 Solutions 44918 1/23/09 5:11 PM Page 343 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–33. The jib crane is supported by a pin at C and rod AB. 4m The rod can withstand a maximum tension of 40 kN. If the A load has a mass of 2 Mg, with its center of mass located at G, determine its maximum allowable distance x and the corresponding horizontal and vertical components of reaction at C. 3.2 m 0.2 m B C G D x 343
25. 25. 5 Solutions 44918 1/23/09 5:11 PM Page 344 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–34. Determine the horizontal and vertical components of reaction at the pin A and the normal force at the smooth 0.4 m C peg B on the member. 30Њ 0.4 m F ϭ 600 N B 30Њ A 344
26. 26. 5 Solutions 44918 1/23/09 5:11 PM Page 345 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–35. The framework is supported by the member AB 4 ft which rests on the smooth floor. When loaded, the pressure distribution on AB is linear as shown. Determine the length d of member AB and the intensity w for this case. 7 ft 800 lb A B w d 345
27. 27. 5 Solutions 44918 1/23/09 5:11 PM Page 346 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–36. Outriggers A and B are used to stabilize the crane from overturning when lifting large loads. If the load to be 4.5 m lifted is 3 Mg, determine the maximum boom angle u so that the crane does not overturn. The crane has a mass of 5 Mg and center of mass at GC, whereas the boom has a mass of 0.6 Mg and center of mass at GB. GB 5m GC u 2.8 m A B 0.7 m 2.3 m 346
28. 28. 5 Solutions 44918 1/23/09 5:11 PM Page 347 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–37. The wooden plank resting between the buildings deflects slightly when it supports the 50-kg boy. This A B deflection causes a triangular distribution of load at its ends, having maximum intensities of wA and wB. Determine wA wB and wB, each measured in N>m, when the boy is standing wA 3 m from one end as shown. Neglect the mass of the plank. 3m 6m 0.45 m 0.3 m 347
29. 29. 5 Solutions 44918 1/23/09 5:11 PM Page 348 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–38. Spring CD remains in the horizontal position at all times due to the roller at D. If the spring is unstretched when u = 0° and the bracket achieves its equilibrium D k C 0.45 m position when u = 30°, determine the stiffness k of the spring and the horizontal and vertical components of 0.6 m reaction at pin A. B u F ϭ 300 N A 348
30. 30. 5 Solutions 44918 1/23/09 5:11 PM Page 349 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–39. Spring CD remains in the horizontal position at all times due to the roller at D. If the spring is unstretched when u = 0° and the stiffness is k = 1.5 kN>m, determine D k C 0.45 m the smallest angle u for equilibrium and the horizontal and vertical components of reaction at pin A. 0.6 m B u F ϭ 300 N A 349
31. 31. 5 Solutions 44918 1/23/09 5:11 PM Page 350 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–40. The platform assembly has a weight of 250 lb and center of gravity at G1. If it is intended to support a maximum load of 400 lb placed at point G2, determine the smallest counterweight W that should be placed at B in G2 order to prevent the platform from tipping over. 2 ft 6 ft G1 8 ft B C D 6 ft 1 ft 1 ft 350
32. 32. 5 Solutions 44918 1/23/09 5:11 PM Page 351 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–41. Determine the horizontal and vertical components of reaction at the pin A and the reaction of the smooth C collar B on the rod. 450 lb 300 lb B D 30Њ A 4 ft 2 ft 1 ft 1 ft 351
33. 33. 5 Solutions 44918 1/23/09 5:11 PM Page 352 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–42. Determine the support reactions of roller A and the A smooth collar B on the rod. The collar is fixed to the rod 900 N AB, but is allowed to slide along rod CD. 1m 1m C 45Њ 2m B 600 N и m D 45Њ 352
34. 34. 5 Solutions 44918 1/23/09 5:11 PM Page 353 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–43. The uniform rod AB has a weight of 15 lb. Determine the force in the cable when the rod is in the position shown. B 5 ft 30Њ A C 10Њ T *5–44. Determine the horizontal and vertical components 500 N of force at the pin A and the reaction at the rocker B of the 200 N curved beam. 10Њ 15Њ 2m A B 353
35. 35. 5 Solutions 44918 1/23/09 5:11 PM Page 354 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–45. The floor crane and the driver have a total weight of 2500 lb with a center of gravity at G. If the crane is required to lift the 500-lb drum, determine the normal 12 ft F reaction on both the wheels at A and both the wheels at B when the boom is in the position shown. 3 ft D C 30Њ 6 ft G E A B 8.4 ft 2.2 ft 1.4 ft 354
36. 36. 5 Solutions 44918 1/23/09 5:11 PM Page 355 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–46. The floor crane and the driver have a total weight of 2500 lb with a center of gravity at G. Determine the largest weight of the drum that can be lifted without causing the 12 ft F crane to overturn when its boom is in the position shown. 3 ft D C 30Њ 6 ft G E A B 8.4 ft 2.2 ft 1.4 ft 355
37. 37. 5 Solutions 44918 1/23/09 5:11 PM Page 356 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–47. The motor has a weight of 850 lb. Determine the 850 lb force that each of the chains exerts on the supporting hooks at A, B, and C. Neglect the size of the hooks and the 0.5 ft thickness of the beam. 1 ft 1.5 ft A C B 10Њ 10Њ 30Њ *5–48. Determine the force P needed to pull the 50-kg roller P over the smooth step. Take u = 60°. u 0.1 m B 0.6 m A 20Њ 356
38. 38. 5 Solutions 44918 1/23/09 5:11 PM Page 357 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–49. Determine the magnitude and direction u of the P minimum force P needed to pull the 50-kg roller over the smooth step. u 0.1 m B 0.6 m A 20Њ 357
39. 39. 5 Solutions 44918 1/23/09 5:11 PM Page 358 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–50. The winch cable on a tow truck is subjected to a force of T = 6 kN when the cable is directed at u = 60°. Determine the magnitudes of the total brake frictional G u 3m force F for the rear set of wheels B and the total normal 1.25 m T forces at both front wheels A and both rear wheels B for A B F equilibrium. The truck has a total mass of 4 Mg and mass center at G. 2m 2.5 m 1.5 m 358
40. 40. 5 Solutions 44918 1/23/09 5:11 PM Page 359 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–51. Determine the minimum cable force T and critical angle u which will cause the tow truck to start tipping, i.e., for the normal reaction at A to be zero. Assume that the truck is G u 3m braked and will not slip at B. The truck has a total mass of 4 Mg and mass center at G.x 1.25 m T A B F 2m 2.5 m 1.5 m *5–52. Three uniform books, each having a weight W and length a, are stacked as shown. Determine the maximum distance d that the top book can extend out from the bottom one so the stack does not topple over. a d 359
41. 41. 5 Solutions 44918 1/23/09 5:11 PM Page 360 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–53. Determine the angle u at which the link ABC is held in equilibrium if member BD moves 2 in. to the right. The springs are originally unstretched when u = 0°. Each kCF ϭ 100 lb/ft C spring has the stiffness shown. The springs remain F horizontal since they are attached to roller guides. u 6 in. D F B 6 in. E kAE ϭ 500 lb/ft A 360
42. 42. 5 Solutions 44918 1/23/09 5:11 PM Page 361 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–54. The uniform rod AB has a weight of 15 lb and the 6 ft spring is unstretched when u = 0°. If u = 30°, determine the stiffness k of the spring. u A k 3 ft B 5–55. The horizontal beam is supported by springs at its 800 N ends. Each spring has a stiffness of k = 5 kN>m and is originally unstretched so that the beam is in the horizontal position. Determine the angle of tilt of the beam if a load of C 800 N is applied at point C as shown. A B 1m 3m 361
43. 43. 5 Solutions 44918 1/23/09 5:11 PM Page 362 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–56. The horizontal beam is supported by springs at its 800 N ends. If the stiffness of the spring at A is kA = 5 kN>m, determine the required stiffness of the spring at B so that if C the beam is loaded with the 800 N it remains in the horizontal position. The springs are originally constructed A B so that the beam is in the horizontal position when it is unloaded. 1m 3m 362
44. 44. 5 Solutions 44918 1/23/09 5:11 PM Page 363 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–57. The smooth disks D and E have a weight of 200 lb and 100 lb, respectively. If a horizontal force of P = 200 lb 5 1.5 ft 4 is applied to the center of disk E, determine the normal 1 ft 3 reactions at the points of contact with the ground at A, B, D P and C. A E B C 363
45. 45. 5 Solutions 44918 1/23/09 5:11 PM Page 364 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–58. The smooth disks D and E have a weight of 200 lb and 100 lb, respectively. Determine the largest horizontal 5 1.5 ft 4 force P that can be applied to the center of disk E without 1 ft 3 causing the disk D to move up the incline. D P A E B C 364
46. 46. 5 Solutions 44918 1/23/09 5:11 PM Page 365 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–59. A man stands out at the end of the diving board, which is supported by two springs A and B, each having a stiffness of k = 15 kN>m. In the position shown the board is horizontal. If the man has a mass of 40 kg, determine the angle of tilt which the board makes with the horizontal after he jumps off. Neglect the weight of the board and assume it 1m 3m is rigid. A B 365
47. 47. 5 Solutions 44918 1/23/09 5:11 PM Page 366 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–60. The uniform rod has a length l and weight W. It is supported at one end A by a smooth wall and the other end by a cord of length s which is attached to the wall as shown. Show that for equilibrium it is required that C h = [(s2 - l2)>3]1>2. h s A l B 366
48. 48. 5 Solutions 44918 1/23/09 5:11 PM Page 367 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–61. If spring BC is unstretched with u = 0° and the bell crank achieves its equilibrium position when u = 15°, k ϭ 2 kN/m C B determine the force F applied perpendicular to segment AD and the horizontal and vertical components of reaction F 150Њ at pin A. Spring BC remains in the horizontal postion at all times due to the roller at C. 300 mm u A D 400 mm 367
49. 49. 5 Solutions 44918 1/23/09 5:11 PM Page 368 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–62. The thin rod of length l is supported by the smooth a tube. Determine the distance a needed for equilibrium if A the applied load is P. 2r B l P 368
50. 50. 5 Solutions 44918 1/23/09 5:11 PM Page 369 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–63. The cart supports the uniform crate having a mass of 85 kg. Determine the vertical reactions on the three casters B at A, B, and C. The caster at B is not shown. Neglect the 0.1 m A mass of the cart. 0.4 m 0.2 m 0.2 m 0.5 m C 0.35 m 0.6 m 0.35 m 369
51. 51. 5 Solutions 44918 1/23/09 5:11 PM Page 370 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–64. The pole for a power line is subjected to the two z cable forces of 60 lb, each force lying in a plane parallel to the x-y plane. If the tension in the guy wire AB is 80 lb, determine the x, y, z components of reaction at the fixed base of the pole, O. 60 lb 45Њ 1 ft 45Њ A 4 ft 60 lb 80 lb 10 ft B 3 ft O y x 370
52. 52. 5 Solutions 44918 1/23/09 5:11 PM Page 371 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–65. If P = 6 kN, x = 0.75 m and y = 1 m, determine z the tension developed in cables AB, CD, and EF. Neglect the weight of the plate. B F P D A x y E x C 2m y 2m 371
53. 53. 5 Solutions 44918 1/23/09 5:11 PM Page 372 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–66. Determine the location x and y of the point of z application of force P so that the tension developed in cables AB, CD, and EF is the same. Neglect the weight of the plate. B F P D A x y E x C 2m y 2m 372
54. 54. 5 Solutions 44918 1/23/09 5:11 PM Page 373 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–67. Due to an unequal distribution of fuel in the wing z tanks, the centers of gravity for the airplane fuselage A and wings B and C are located as shown. If these components have weights W = 45 000 lb, W = 8000 lb, A B and W = 6000 lb, determine the normal reactions of the C wheels D, E, and F on the ground. D B A C E F y 8 ft 4 ft 6 ft 20 ft 8 ft 3 ft x 6 ft 373
55. 55. 5 Solutions 44918 1/23/09 5:11 PM Page 374 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. *5–68. Determine the magnitude of force F that must be z exerted on the handle at C to hold the 75-kg crate in the position shown. Also, determine the components of reaction at the thrust bearing A and smooth journal bearing B. A 0.1 m B 0.6 m x 0.5 m y 0.2 m C 0.1 m F 374
56. 56. 5 Solutions 44918 1/23/09 5:11 PM Page 375 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. •5–69. The shaft is supported by three smooth journal z bearings at A, B, and C. Determine the components of 900 N reaction at these bearings. 600 N 450 N C A 0.6 m 0.9 m 0.6 m 0.9 m x 0.9 m B 0.9 m y 500 N 0.9 m 375
57. 57. 5 Solutions 44918 1/23/09 5:11 PM Page 376 © 2010 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 5–70. Determine the tension in cables BD and CD and z the x, y, z components of reaction at the ball-and-socket joint at A. D 3m 300 N B A 1.5 m x 0.5 m C 1m y 376