Physics (5th Edition)
5th Edition
ISBN: 9780321976444
Author: James S. Walker
Publisher: PEARSON
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Chapter 11, Problem 78GP
To determine
The mass of the tail required for the balance.
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A man holds a 192-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 24.2 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. Please show how the angle in c was found
A steel ladder of mass 40 kg and of length 20 m leans against a frictionless wall at a point 16 m above the ground. For safety purpose, the center of mass of the ladder is designed to be a quarter the way up. A 60 kg man is standing halfway up the ladder. (a) Calculate the reaction R from the ground and the angle θ it makes with the vertical. (b) If the man is to stand on the top of the ladder without slipping, find the minimum value for the coefficient of static friction between the ladder and the ground.
A man holds a 169-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 , which is applied perpendicular to the forearm. The forearm weighs 22.2 N and has a center of gravity as indicated. Find (a) the magnitude of 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.
Chapter 11 Solutions
Physics (5th Edition)
Ch. 11.1 - A bicycle wheel is mounted on an axle, as shown in...Ch. 11.2 - Consider two objects with the following...Ch. 11.3 - A Physics sign is supported symmetrically by two...Ch. 11.4 - A mobile made from three piggy banks (A, B, C) is...Ch. 11.5 - Prob. 5EYUCh. 11.6 - Consider two objects with the following...Ch. 11.7 - Prob. 7EYUCh. 11.8 - In system 1, a torque of 20 N m acts through an...Ch. 11.9 - The angular velocity of the spinning bicycle wheel...Ch. 11 - Two forces produce the same torque. Does it follow...
Ch. 11 - A car pitches down in front when the brakes are...Ch. 11 - A tightrope walker uses a long pole to aid in...Ch. 11 - When a motorcycle accelerates rapidly from a stop...Ch. 11 - Give an example of a system in which the net...Ch. 11 - Give an example of a system in which the net force...Ch. 11 - Is the normal force exerted by the ground the same...Ch. 11 - Give two everyday examples of objects that are not...Ch. 11 - Give two everyday examples of objects that are in...Ch. 11 - Can an object have zero translational acceleration...Ch. 11 - Stars form when a large rotating cloud of gas...Ch. 11 - What purpose does the tail rotor on a helicopter...Ch. 11 - Is it possible to change the angular momentum of...Ch. 11 - Suppose a diver springs into the air with no...Ch. 11 - To tighten a spark plug, it is recommended that a...Ch. 11 - Pulling a Weed The gardening tool shown in Figure...Ch. 11 - A person slowly lowers a 3.6-kg crab trap over the...Ch. 11 - A squirrel-proof bird feeder has a lever that...Ch. 11 - At one position during its cycle, the foot pushes...Ch. 11 - BIO Predict/Calculate Force to Hold a Baseball A...Ch. 11 - At the local playground, a 21-kg child sits on the...Ch. 11 - Predict/Explain Consider the pulley-block systems...Ch. 11 - Suppose a torque rotates your body about one of...Ch. 11 - A torque of 0.97 N m is applied to a bicycle...Ch. 11 - When a ceiling fan rotating with an angular speed...Ch. 11 - When the play button is pressed, a CD accelerates...Ch. 11 - A person holds a ladder horizontally at its...Ch. 11 - A 0.180-kg wooden rod is 1.25 m long and pivots at...Ch. 11 - Predict/Calculate A wheel on a game show is given...Ch. 11 - The L-shaped object in Figure 11-41 consists of...Ch. 11 - The L-shaped object described in the previous...Ch. 11 - A motorcycle accelerates from rest, and both the...Ch. 11 - Predict/Calculate A torque of 13 N m is applied...Ch. 11 - Predict/Explain Suppose the person in Example...Ch. 11 - A string that passes over a pulley has a 0.321-kg...Ch. 11 - To loosen the lid on a jar of jam 7.6 cm in...Ch. 11 - BIO Predict/Calculate Referring to the person...Ch. 11 - Prob. 24PCECh. 11 - Prob. 25PCECh. 11 - Predict/Calculate A schoolyard teeter-totter with...Ch. 11 - A 0.122-kg remote control 23.0 cm long rests on a...Ch. 11 - Predict/Calculate A 0.16-kg meterstick is held...Ch. 11 - Prob. 29PCECh. 11 - A uniform metal rod, with a mass of 2.0 kg and a...Ch. 11 - Prob. 31PCECh. 11 - In Figure 11-46 two acrobats perform a balancing...Ch. 11 - BIO Forces in the Foot In Figure 11-47 we see the...Ch. 11 - A stick with a mass of 0.214 kg and a length of...Ch. 11 - Prob. 35PCECh. 11 - If the cat in Example 11-9 has a mass of 3.9 kg,...Ch. 11 - Prob. 37PCECh. 11 - Maximum Overhang Three identical, uniform books of...Ch. 11 - A baseball bat balances 71.1 cm from one end. If a...Ch. 11 - A 2.85-kg bucket is attached to a rope wrapped...Ch. 11 - A child exerts a tangential 53 4-N force on the...Ch. 11 - Predict/Calculate You pull downward with a force...Ch. 11 - One elevator arrangement includes the passenger...Ch. 11 - Atwood's Machine An Atwoods machine consists of...Ch. 11 - A 1.4-kg bicycle tire with a radius of 33 cm...Ch. 11 - Jogger 1 in Figure 11-51 has a mass of 65.3 kg and...Ch. 11 - Predict/Calculate Suppose jogger 3 in Figure 11-51...Ch. 11 - A torque of 0.12 N m is applied to an egg beater...Ch. 11 - A windmill has an initial angular momentum of 8500...Ch. 11 - Two gerbils run in place with a linear speed of...Ch. 11 - Predict/Explain A student rotates on a...Ch. 11 - A puck on a horizontal, frictionless surface is...Ch. 11 - A puck on a horizontal, frictionless surface is...Ch. 11 - As an ice skater begins a spin, his angular speed...Ch. 11 - A disk-shaped merry-go-round of radius 2.63 m and...Ch. 11 - A student sits at rest on a piano stool that can...Ch. 11 - Predict/Calculate A turntable with a moment of...Ch. 11 - A student on a piano stool rotates freely with an...Ch. 11 - Walking on a Merry-Go-Round A child of mass m...Ch. 11 - Predict/Explain Two spheres of equal mass and...Ch. 11 - Turning a doorknob through 0.25 of a revolution...Ch. 11 - A person exerts a tangential force of 36.1 N on...Ch. 11 - To prepare homemade ice cream a crank must be...Ch. 11 - Power of a Dental Drill A popular make of dental...Ch. 11 - For a home repair job you must turn the handle of...Ch. 11 - The L-shaped object in Figure 11-40 consists of...Ch. 11 - The rectangular object in Figure 11-41 consists of...Ch. 11 - Predict/Calculate A circular saw blade accelerates...Ch. 11 - CE A uniform disk stands upright on its edge, and...Ch. 11 - CE Consider the two rotating systems shown in...Ch. 11 - CE Predict/Explain A disk and a hoop (bicycle...Ch. 11 - CE A beetle sits at the nm of a turntable that is...Ch. 11 - After getting a drink of water a hamster jumps...Ch. 11 - A 47.0-kg uniform rod 4.25 m long is attached to a...Ch. 11 - Prob. 75GPCh. 11 - BIO The Masseter Muscle The masseter muscle, the...Ch. 11 - Exercising the Biceps You are designing exercise...Ch. 11 - Prob. 78GPCh. 11 - In Example 11-11, suppose the ladder is uniform,...Ch. 11 - When you arrive at Dukes Dude Ranch you are...Ch. 11 - Prob. 81GPCh. 11 - Flats Versus Heels A woman might wear a pair of...Ch. 11 - BIO A young girl sits at the edge of a dock by the...Ch. 11 - BIO Deltoid Muscle A crossing guard holds a STOP...Ch. 11 - BIO Triceps To determine the force a persons...Ch. 11 - Predict/Calculate Suppose partial melting of the...Ch. 11 - A bicycle wheel of radius R and mass M is at rest...Ch. 11 - A 0.101-kg yo-yo has an outer radius R that is...Ch. 11 - BIO Peak Pedaling Torque The downward force...Ch. 11 - A cylinder of mass m and radius r has a string...Ch. 11 - Bricks in Equilibrium Consider a system of four...Ch. 11 - BIO Correcting Torsiversion Torsiversion is a...Ch. 11 - BIO Correcting Torsiversion Torsiversion is a...Ch. 11 - BIO Correcting Torsiversion Torsiversion is a...Ch. 11 - BIO Correcting Torsiversion Torsiversion is a...Ch. 11 - Referring to Example 11-14 Suppose the mass of the...Ch. 11 - Prob. 97PPCh. 11 - Referring to Quick Example 11-22 Suppose the child...Ch. 11 - Referring to Quick Example 11-22 Suppose...
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- Two children of mass 20.0 kg and 30.0 kg sit balanced on a seesaw with the pivot point located at the center of the seesaw. If the children are separated by a distance of 3.00 m, at what distance from the pivot point is the small child sitting in order to maintain the balance?arrow_forwardIn order to get his car out of the mud, a man ties one end of a rope to the front bumper and the other end to a tee 15 m away as shown below. He then pulls on the center of the rope with a force of 400 N, which causes its center to be displaced 0.30 m, as shown. What is the force of the rope on the car?arrow_forwardSuppose a 900-kg car is on the bridge in Figure 9.34 with its center of mass halfway between the hinges and the cable attachments. (The bridge is supported by the cables and hinges only.) (a) Find the force in the cables. (b) Find the direction and magnitude of the force exerted by the hinges on the bridge.arrow_forward
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- Suppose a horse leans against a wall as in Figure 9.31. Calculate the force exerted on the wall assuming that force is horizontal while using the data in the schematic representation of the situation. Note that the force exerted on the wall is equal in magnitude and opposite in direction to the force exerted on the horse, keeping it in equilibrium. The total mass of the horse and rider is 500 kg. Take the data to be accurate to three digits.arrow_forwardthe figure shows a horizontal human arm lifting a dumbbell. the forearm is in equilibrium under the action of the weight w of the dumbbell, the tension t in the tendon connected to the biceps muscle, and the force e exerted on the forearm by the upper arm at the elbow joints. we neglect the weight of the forearm itself. (for clarity, the point a where the tendon is attached is drawn farther from the elbow than its actual position.) given the weight w and the angle between the tension force and the horizontal, find t and the two components of ē (three unknown scalar quantities in all)arrow_forwardThe center of gravity of a 60-kg stroke patient is located at a 70-cm mark. If the patient is supported at 65 cm, where must an 80-g object be hung in order to attain equilibrium? The biceps muscle exerts a vertical force of 7090 N on the lower arm. Calculate (a.) The torque about the axis of rotation through the elbow joint if the biceps and lower arm are perpendicular to each other (b.) If the lower arm is 30 ° lower with respect to the horizontal. Assume that the muscle is attached 5.0 cm from the elbow.arrow_forward
- A seesaw consisting of a uniform board of mass M and length ℓ supportsat rest a father and daughter with masses mf and md, respectively, as shown. The support (called the fulcrum) is under the center of gravity of the board, the father is a distance d from the center, and the daughter is a distance ℓ/2 from the center. (A) Determine the magnitude of the upward force n→ exerted by the support on the board.arrow_forwardIn an isometric exercise a person places a hand on a scale and pushes vertically downward, keeping the forearm horizontal. This is possible because the triceps muscle applies an upward force M perpendicular to the arm, as the drawing indicates. The forearm weighs 24.0 N and has a center of gravity as indicated. The scale registers 103 N. Determine the magnitude of M. Narrow_forwardAs a part of his daily workout routine, he lifts 10-kg dumbbells on each hand. His hands, and forearms weigh 4 kg each. If the length of each of his forearms and hands are 0.5 m, determine the force exerted by his muscles? Assume that the center of gravity of the, forearms are in the middle.arrow_forward
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