A vertical steel girder( عارضة خشبية ) with a cross sectional area of 0.15 m2has a 1550kg sign hanging from its end. (Ignore the mass of the girder itself.) a)What is the stress within the girder? b)What is the strain on the girder? c)If the girder is 9.50 m long, how much is it lengthened?

A steel cable 2.00 m in length and with cross-sectional radius 0.350 mm is used to suspend from the ceiling a 10.0-kg model aircraft that is flying in a horizontal circle with an angular speed of 6.00 rad/s. What is the strain produced in the cable?

Two thin rods, one made of steel and the other of aluminium, are joined end to end. Each rod is 2.0m long and has cross-sectional area 9.1mm2 . If a 10,000N tensile force is applied at each end of the combination, find: (a) stress in each rod; (b) strain in each rod; and, (c) elongation of each rod.

What Is Static Equilibrium? Problems 13 are grouped. 1. C A ball is attached to a strong, lightweight rod (Fig. P14.1). The rod is supported by a horizontal pin near the top. The ball is at rest. Is the ball in static equilibrium? If not, why not? If so, which type of equilibrium is itstable, unstable, or neutral? Hint: What would happen if you displaced the ball slightly? FIGURE P14.1

Assume Youngs modulus for bone is 1.50 1010 N/m2. The bone breaks if stress greater than 1.50 108 N/m2 is imposed on it. (a) What is the maximum force that can be exerted on the femur bone in the leg if it has a minimum effective diameter of 2.50 cm? (b) If this much force is applied compressively, by how much does the 25.0-cm-long bone shorten?

Suppose the weight of the drawbridge in Figure 9.34 is supported entirely by its hinges and the opposite shore, so that its cables are slack. (a) What fraction of the weight is supported by the opposite shore if the point of support is directly beneath the cable attachments? (b) What is the direction and magnitude of the force the hinges exert on the bridge under these circumstances? The mass of the bridge is 2500 kg.

The keystone of an arch is the stone at the top (Fig. P14.9). It is supported by forces from its two neighbors, blocks A and B. Each block has mass m and approximate length L. What can you conclude about the force exerted by each block, FA and FB, for the keystone to remain in static equilibrium? That is, show that the equilibrium conditions are satisfied by the components of the forces FAx, FAy, FBx, and FBy. Assume the arch is symmetric. FIGURE P14.9

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=1.51104N

Problems 33 and 34 are paired. One end of a uniform beam that weighs 2.80 102 N is attached to a wall with a hinge pin. The other end is supported by a cable making the angles shown in Figure P14.33. Find the tension in the cable. FIGURE P14.33 Problems 33 and 34.

A suspender rod of a suspension bridge is 25.0 m long. If the rod is made of steel, what must its diameter be so that it does not stretch more than 1.0 cm when a 2.5104kg tuck passes by it? Assume that the rod supports all of the weight of the truck.