67. A 15.0-kg ball is supported from the ceiling by rope A. Rope B pulls downward and to the side on the ball. If the angle A of A to the vertical is 22° and if B makes an angle of 53° to the ver- tical (Fig. 9-85), find the tensions in ropes A and B. 22° В 53° FIGURE 9-85 Problem 67.

Two identical, uniform beams are symmetrically set up against each other (Fig. 9–87) on a floor with which they have a coefficient of fric- tion µs = 0.50. What is the minimum angle the beams can make with the floor and still not fall? FIGURE 9-87 Problem 71.

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- 5. Two identical, uniform beams of length 3 m and weighing 260 N each are connected at one end by a frictionless hinge. A light horizontal crossbar, attached at the midpoints of the beams maintains an angle 50° between the beams. The beams are suspended from the ceiling by vertical wires so they form a V. See figure. (a) What force does the crossbar exert on each beam? (b) Is the crossbar under compression or tension, i.e. are the ends of the crossbar being pushed together or stretched farther apart? (c) What force (magnitude and direction) does the hinge exert on each beam? Crossbar Hinge

(II) A 0.75-kg sheet is centered on a clothesline as shown in Fig. 9-63. The clothesline on either side of the hanging sheet makes an angle of 3.5° with the horizontal. Calculate the tension in the clothesline (ignore its mass) on either side of the sheet. Why is the tension so much greater than the weight of the sheet? 3.5° 3.5° FIGURE 9-63 Problem 23.

1. A crowbar lifts a weight in Fig. 10-21 below. A downward force on the long end of the crowbar, F₁, equals 225 N. How much weight must be held up by the upward force, F2, being exerted by the short end? The value of r₁-perpendicular is equal to 0.300 m and that of r₂-perpendicular is 0.0500 m. Ans. 1350 N upward. 冰 5.00 cm 30.0 cm- Fig. 10-21

A B 3.0 m 1.0 m Copyright 200S Pearson Prentice Hal. Inc. FIGURE 9-42 A 58 kg person stands at tip of diving board. Calculate the forces F and FR that the supports exert on the diving board: (a) Ignore the weight of the board. (b) Take into account the board's mass of 35 kg. Assume the board's CG is at its center.

5) Consider a rigid steel beam of length L = 14.5 m and mass mb = 375 kg resting on two supports, one at each end. A worker of mass mw = 76 kg sits on the beam at a distance x from support A. Refer to the figure, though note that it is not drawn to scale. a) Enter an expression for the force support B must exert on the beam in order for it to remain at rest, in terms of defined quantities, x, and g.  b) When the worker sits at a distance x = 7.5 m from support A, calculate the force, in newtons, that support B must exert on the beam in order for it to remain at rest. Use g with three significant figures.  c) The force exerted on the beam by support A is measured and found to be FA = 2390 N. At what distance x, in meters, from support A is the worker sitting now?

5-61. If d = 1 m, and 0 = 30°, determine the normal reaction at the smooth supports and the required distance a for the placement of the roller if P 600 N. Neglect the weight of the bar. =

blem 3 ne mass of the concrete block is 880kg, how big are the forces in two ropes? A) 400N B) 500N CC)300N D)CD) 600N E)Ⓡ F₂ 20 F 120 400 N { F)350N