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Knocking Over a Post. One end of a post weighing 400 N and with height h rests on a rough horizontal surface with μs = 0.30. The upper end is held by a rope fastened to the surface and making an angle of 36.9° with the post (Fig. P11.90). A horizontal force
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- In Example 14.3, we found that one of the steel cables supporting an airplane at the Udvar-Hazy Center was under a tension of 9.30 103 N. Assume the cable has a diameter of 2.30 era and an initial length of 8.00 m before the plane is suspended on the cable. How much longer is the cable when the plane is suspended on it?arrow_forwardAn aluminium (=2.7g/cm3) wire is suspended from the ceiling and hangs vertically. How long must the wire be before the stress at its upper end reaches the proportionality limit, which is 8.0107N/m2 ?arrow_forwardIn an emergency situation, a person with a broken forearm ties a strap from his hand to clip on his shoulder as in the figure below. His 1.60-kg forearm remains in a horizontal position and the strap makes an angle of 0 = 53.5° with the horizontal. Assume the forearm is uniform, has a length of e = 0.324 m, assume the biceps muscle is relaxed, and ignore the mass and length of the hand. R (a) Find the tension in the strap. (b) Find the components of the reaction force exerted by the humerus on the forearm. (Assume the positive x-direction is to the right and the positive y-direction is upward.) Ry = N R, = Narrow_forward
- In the figure, a lead brick rests horizontally on cylinders A and B. The areas of the top faces of the cylinders are related by A4= 2.8 Ag; the Young's moduli of the cylinders are related by Ea= 2.3 Eg. The cylinders had identical lengths before the brick was placed on them. What fraction of the brick's mass is supported (a) by cylinder A and (b) by cylinder B? The horizontal distances between the center of mass of the brick and the centerlines of the cylinders are dafor cylinder A and d; for cylinder B. (c) What is the ratio da/dg? com of brick A (a) Number i Units (b) Number i Units (c) Number i Unitsarrow_forwardOne end of a uniform ℓ = 4.40-m-long rod of weight w is supported by a cable at an angle of ? = 37° with the rod. The other end rests against a wall, where it is held by friction (see figure). The coefficient of static friction between the wall and the rod is ?s = 0.570. Determine the minimum distance x from point A at which an additional weight w (the same as the weight of the rod) can be hung without causing the rod to slip at point A._______________________ marrow_forwardChapter 12, Problem 028 GO In the figure, suppose the length L of the uniform bar is 3.1 m and its weight is 240 N. Also, let the block's weight W = 270 N and the angle e = 41°. The wire can withstand a maximum tension of 420 N. (a) What is the maximum possible distance x before the wire breaks? With the block placed at this maximum x, what are the (b) horizontal and (c) vertical components of the force on the bar from the hinge at A? Com (a) Number Units (b) Number Units (c) Number Unitsarrow_forward
- A construction worker attempts to lift a uniform beam off the floor and raise it to a vertical position. The beam is 1.88 m long and weighs 490 N. At a certain instant the worker holds the beam momentarily at rest with one end a distance d = 1.02 m above the floor, as shown in the figure, by exerting a force P→ on the beam. (a) What is the magnitude of P→? (b) What is the magnitude of the (net) force of the floor on the beam? (c) What is the minimum value the coefficient of static friction between beam and floor can have in order for the beam not to slip at this instant?arrow_forwardOne end of a uniform rod of weight w = 73.5 N and length L = 2.55 m is supported by a cable at an angle of ? = 37.0°above the rod. The other end rests on a small frictionless support and presses into a wall as shown in the figure. Determine the magnitude n of the vertical normal force exerted by the support on the rod and find the magnitude T of the tension in the cable.arrow_forwardA 72.0-kg weightlifter doing arm raises holds a 7.50-kg weight. Her arm pivots around the elbow joint, starting 40.0° below the horizontal (Fig. P11.54). Biometric measurements have shown that, together, the forearms and the hands account for 6.00% of a person’s weight. Since the upper arm is held vertically, the biceps muscle always acts verti-cally and is attached to the bones of the forearm 5.50 cm from the elbow joint. The center of mass of this person’s forearm–hand combination is 16.0 cm from the elbow joint, along the bones of the forearm, and she holds the weight 38.0 cm from her elbow joint. (a) Draw a free-body diagram of the forearm. (b) What force does the biceps muscle exert on the forearm? (c) Find the magni-tude and direction of the force that the elbow joint exerts on the forearm. (d) As the weightlifter raises her arm toward a horizontal position, will the force in the biceps muscle increase, decrease, or stay the same? Why? Solve A B C D and show complete solutionarrow_forward
- Your answer is partially correct. The system in the figure is in equilibrium. A concrete block of mass 221 kg hangs from the end of the uniform strut of mass 45.1 kg. For angles = 39.4° and 0 = 55.7°, find (a) the tension T in the cable and the (b) horizontal and (c) vertical components of the force on the strut from the hinge. (a) Number i 98100 (b) Number i (c) Number i T Strut 0 -Hinge Units Units Units N <arrow_forwardA man holds a 183-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force M→, which is applied perpendicular to the forearm. The forearm weighs 24.5 N and has a center of gravity as indicated. Find (a) the magnitude of M→ and the (b) magnitude and (c) direction (as a positive angle counterclockwise from horizontal) of the force applied by the upper arm bone to the forearm at the elbow joint.arrow_forwardA person is sitting with one leg outstretched and stationary, so that it makes an angle of 30.0° with the horizontal, as the drawing indicates. The weight of the leg below the knee is 35.5 N, with the center of gravity located below the knee joint. The leg is being held in this position because of the force M→ applied by the quadriceps muscle, which is attached 0.100 m below the knee joint (see the drawing). Obtain the magnitude of M→.arrow_forward
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