11.12 A uniform aluminum beam 9.00 m long, weighing 300 N, rests symmetrically on two supports 5.00 m apart (Fig. E11.12). A boy weighing 600 N starts at point A and walks toward the right. (a) In the same diagram construct two graphs showing the upward forces FA and FB exerted on the beam at points A and B, as functions of the coordinate x of the boy. Let 1 cm = 100 N vertically, and 1 cm = 1.00 m horizontally. (b) From your diagram, how far beyond point B can the boy walk before the beam tips? (c) How far Figure E11.12 B A

11.12 A uniform aluminum beam 9.00 m long, weighing 300 N, rests symmetrically on two supports 5.00 m apart (Fig. E11.12). A boy weighing 600 N starts at point A and walks toward the right. (a) In the same diagram construct two graphs showing the upward forces FA and FB exerted on the beam at points A and B, as functions of the coordinate x of the boy. Let 1 cm = 100 N vertically, and 1 cm = 1.00 m horizontally. (b) From your diagram, how far beyond point B can the boy walk before the beam tips? (c) How far Figure E11.12 B A

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter10: Rotational Motion

Section: Chapter Questions

Problem 74P: A stepladder of negligible weight is constructed as shown in Figure P10.73, with AC = BC = ℓ. A...

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A stepladder of negligible weight is constructed as shown in Figure P10.73, with AC = BC = ℓ. 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 P10.73 Problems 73 and 74.
Consider a rigid steel beam of length L = 13 m and mass mb = 383 kg resting on two supports, one at each end. A worker of mass mw = 68 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. 1.) the force exerted on on the beam by support A is found to be 2180 N as wht distance x in meters from support A is the worker sitting now?
A horizontal plank 4.00 m long and having mass 20.0 kg restson two supports, one at the left end of the plank and a second1.00 m from the right end of the plank. What is the magnitude of theforce exerted on the plank by the support on the right side?
The taho vendor carries a 1.5 m long light plank over his shoulder. At the ends of the plank are two buckets weighing 40 N and 60 N respectively. (a) Find the value of force F exerted by his shoulder. Neglect the weight of the plank. ( b) Where should he support the plank for it to be balanced horizontally
Consider a rigid steel beam of length L = 11.5 m and mass mb = 405 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. a)When the worker sits at a distance x = 4.5 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. b)The force exerted on the beam by support A is measured and found to be FA = 2180 N. At what distance x, in meters, from support A is the worker sitting now?
A 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 solution
An individual leans forwards to pick up a box of 100 N. The weight of his upper body has a magnitude of 450 N. The back is pivoting around the base of the vertebral column. Consider the back of the individual as a rigid bar that is controlled by a muscle with an angle of 12° (See picture, d = trunk-head distance = 1 m).a) Calculate the magnitude of muscle force required to lift the box.b) Calculate the magnitude of the force at the base of the vertebral column. Hints: For (a) solve the equilibrium of moments, i.e. what force is required in the muscle to balance out the moments acting around the base of the spine.For (b), solve the equilibrium of forces acting on the spine, including the muscle force you’ve just calculated, in x and y separately. There are two extra forces not shown in the diagram: x and y contact forces acting at the base of the spine. These are whatever is needed to keep the total forces acting on the spine = 0 (so the spine isn’t accelerating off in some…
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Problem 8: Consider a rigid steel beam of length L = 11.5 m and mass mb = 412 kg resting on two supports, one at each end. A worker of mass mw = 78 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. Part (a) When the worker sits at a distance x = 4.5 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. Part (b) The force exerted on the beam by support A is measured and found to be FA = 2180 N. At what distance x, in meters, from support A is the worker sitting now?
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Consider a rigid steel beam of length L = 13.5 m and mass mb = 420 kg resting on two supports, one at each end. A worker of mass mw = 61 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. 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.
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 Aa= 2.4 Ag: the Young's moduli of the cylinders are related by EA 1.6 Ea. 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 d,for cylinder A and dg for cylinder B. (c) What is the ratio d,/dg? com of brick