College Physics
1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: OpenStax College
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 9, Problem 16CQ
Swimmers and athletes during competition need to go through certain postures at the beginning of the race. Consider the balance of the person and why start-offs are so important for races.
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
A person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a Wo = 210–N object. The spine and upper body are represented as a uniform horizontal rod of weight Wb = 325 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0
A person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal
supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person
bending forward to lift a Wo = 195-N object. The spine and upper body are represented as a uniform horizontal rod of weight W₁ = 305 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the
way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0⁰.
Back muscle
R₂
T 12.0°
1T
Rx
Pivot
a
Wb
Wo
..(a).Find the tension in the back muscle.
1.114
Enter a number. differs from the correct answer by more than 10%. Double check your calculations. kN…
A person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a Wo = 210–N object. The spine and upper body are represented as a uniform horizontal rod of weight Wb = 325 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°.
a) find the tension on the back muscle.
Answer: ____ kN
b) find the compressional force In The spine.
Answer: ____ kN
Chapter 9 Solutions
College Physics
Ch. 9 - What can you say about the velocity of a moving...Ch. 9 - Under what conditions can a rotating body be in...Ch. 9 - What three factors affect the torque created by a...Ch. 9 - A wrecking ball is being used to knock down a...Ch. 9 - Mechanics put a length of Pipe over the handle of...Ch. 9 - A round pencil lying on its side as in Figure 9.13...Ch. 9 - Explain the need for tall towers on a suspension...Ch. 9 - When visiting some countries, you may see a person...Ch. 9 - Scissors are like a double-lever "Stem, Which of...Ch. 9 - Suppose you pull a nail at a constant rate using a...
Ch. 9 - Why are the forces exerted on the outside world by...Ch. 9 - Explain why the forces in our joints are several...Ch. 9 - Why are the forces exerted on the outside world by...Ch. 9 - Explain why the forces in our joints are several...Ch. 9 - Certain of dinosaurs were bipedal (walked on two...Ch. 9 - Swimmers and athletes during competition need to...Ch. 9 - If the maximum force the biceps muscle can exert...Ch. 9 - Suppose the biceps muscle was attached through...Ch. 9 - Explain one of the reasons why pregnant women...Ch. 9 - (a) When opening a door, you push on it...Ch. 9 - When tightening a bolt, you push perpendicularly...Ch. 9 - Two children push on opposite sides of a door...Ch. 9 - Use the second condition for equilibrium (net =0 )...Ch. 9 - Repeat the seesaw problem in Example 9.1 with the...Ch. 9 - Suppose a horse leans against a wall as in Figure...Ch. 9 - Two children of mass 20.0 kg and 30.0 kg sit...Ch. 9 - (a) Calculate the magnitude and direction of the...Ch. 9 - A person carries a plank of wood 2.00 m long with...Ch. 9 - A 17.0-m-high and 11.0-m-long wall under...Ch. 9 - (a) What force must be exerted by the wind to...Ch. 9 - Suppose the weight of the drawbridge in Figure...Ch. 9 - Suppose a 900-kg car is on the bridge in Figure...Ch. 9 - A sandwich board advertising sign is constructed...Ch. 9 - (a) What minimum coefficient of friction is needed...Ch. 9 - A gymnast is attempting to perform splits. From...Ch. 9 - To get up on the roof, a person (mass 70.0 kg)...Ch. 9 - In Figure 9.21, the cg of the pole held by the...Ch. 9 - What is the mechanical advantage of a nail puller...Ch. 9 - Suppose you needed to raise a 250-kg mower a...Ch. 9 - a) What is the mechanical advantage of a...Ch. 9 - A typical car has an axle with 1.10 cm radius...Ch. 9 - What force does the nail puller in Exercise 9.19...Ch. 9 - If you used an ideal pulley of the type shown in...Ch. 9 - Repeat Exercise 9.24 for the pulley shown in...Ch. 9 - Verity that the force in the elbow joint in...Ch. 9 - Two muscles in the back of the leg pull on the...Ch. 9 - The upper leg muscle (quadriceps) exerts a force...Ch. 9 - A device for exercising the upper leg muscle is...Ch. 9 - A person working at a drafting board may hold her...Ch. 9 - We analyzed the biceps muscle example with the...Ch. 9 - Even when the head is held erect, as in Figure...Ch. 9 - A 75-kg man stands on his toes by exerting an...Ch. 9 - A father lifts his child as shown in Figure 9.43....Ch. 9 - Unlike most of the other muscles in our bodies,...Ch. 9 - Integrated Concepts Suppose we replace the 4.0-kg...Ch. 9 - (a) What force should the woman in Figure 9.45...Ch. 9 - You have just planted a sturdy 2-m-tall palm tree...Ch. 9 - Unreasonable Results Suppose two children are...Ch. 9 - Construct Your Own Problem Consider a method for...
Additional Science Textbook Solutions
Find more solutions based on key concepts
1. An object is subject to two forces that do not point in opposite directions. Is it possible to choose their ...
College Physics: A Strategic Approach (3rd Edition)
Check Your Understanding A Carnot engine operates between reservoirs at 400 and 30 . (a) What is the efficienc...
University Physics Volume 2
The force, when you push against a wall with your fingers, they bend.
Conceptual Physics (12th Edition)
l. Suppose you have the uniformly charged cube in FIGURE Q24.1. Can you use symmetry alone to deduce the shape ...
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
1. A person gets in an elevator on the ground floor and rides it to the top floor of a building. Sketch a veloc...
College Physics: A Strategic Approach (4th Edition)
13. A 50 kg box hangs from rope. What is the tension in the rope if:
a. The box is at rest?
b. The box moves ...
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- A person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a W 170-N object. The spine and upper body are represented as a uniform horizontal rod of weight W = 355 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°. Back muscle Pivot = a R₂ T 12.0° Rx Wb Wo (i) (a) Find the tension in the back muscle. 1.114 Your response differs from the correct answer by more than 10%. Double check your calculations. kN (b)…arrow_forwardA person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a Wo = 215–N object. The spine and upper body are represented as a uniform horizontal rod of weight Wb = 330 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°. (a) Find the tension in the back muscle. (b) Find the compressional force in the spine. (Enter the magnitude.)arrow_forwardA person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a Wo = 195–N object. The spine and upper body are represented as a uniform horizontal rod of weight Wb = 290 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°. In figure (a), a man bends his back forward to lift a set of weights. The hips are labeled as the pivot and the back muscle is also labeled to the right of the pivot. In figure (b), a…arrow_forward
- A person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a Wo = 195–N object. The spine and upper body are represented as a uniform horizontal rod of weight Wb = 290 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°. In figure (a), a man bends his back forward to lift a set of weights. The hips are labeled as the pivot and the back muscle is also labeled to the right of the pivot. In figure (b), a…arrow_forwardA person bending forward to lift a load "with his back" (Figure a) rather than "with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a W. 195-N object. The spine and upper %3D body are represented as a uniform horizontal rod of weight W, = 335 N pivoted at the base of the spine. The erector spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0°. Back muscle R, T 12.0° Pivot R W. Wh (a) Find the tension in the back muscle. kN (b) Find the compressional force in the spine. (Enter the magnitude.) kNarrow_forwardA person bending forward to lift a load "with his back" (Figure a) rather than with his knees" can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in Figure b, of a person bending forward to lift a W-195-N object. The spine and upper body are represented as a uniform horizontal rod of weight W-295 N pivoted at the base of the spine. The erector spinalls muscle, attached at a point two-thirds of the way up the spine, maintains the position of the back. The angle between the spine and this muscle is 12.0° Back muscle Pivot R₂ T120 T W W₂ 0 (a) Find the tension in the back muscle. KN D (b) Find the compressional force in the spine. (Enter the magnitude.) KNarrow_forward
- You can find the center of gravity of a meter stick by resting it horizontally on your two index fingers, and then slowly drawing your fingers together. First the meter stick will slip on one finger, and then on the other, but eventually the fingers meet at the CG. Why does this work?arrow_forwardYou can find the center of gravity of a long ruler by resting it horizontally on your two index fingers, and then slowly drawing your fingers together. First the ruler will slip on one finger, and then on the other, but eventually the fingers meet at the CG. Why does this workarrow_forwardEven when the head is held erect, as in Figure shown, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. Calculate the force exerted by these muscles using the information in the figure.arrow_forward
- Stand with your heels and back against a wall and try to bend over and touch your toes. You’ll find that you have to stand away from the wall to do so without toppling over. Compare the minimum distance of your heels from the wall with that of a friend of the opposite sex. Who can touch their toes with their heels nearer to the wall males or females? On the average and in proportion to height, which sex has the lower center of gravity?arrow_forwardEven when the head is held erect, as in the figure below, its center of mass is not directly over the principal point of support (the atlanto-occipital joint). The muscles in the back of the neck must therefore exert a force to keep it erect. That is why your head falls forward when you fall asleep in class. If the perpendicular distance between the line of action for the weight of the head and the pivot point is rW⊥ = 2.0 cmand the perpendicular distance between the line of action for the force the muscles exert on the head and the pivot point is rM⊥ = 4.6 cm, determine each of the following. (Assume the weight of the head is 50 N.) (a) the force exerted by these muscles(b) the force on the point of supportarrow_forwardBIO When a gymnast performing on the rings executes the iron cross, he maintains the position at rest shown in Figure P10.85a. In this maneuver, the gymnasts feet (not shown) are off the floor. The primary muscles involved in supporting this position are the latissimus dorsi (lats) and the pectoralis major (pecs). One of the rings exerts an upward fore Fh on a hand as shown in Figure P10.85b. The force Fs is exerted by the shoulder joint on the arm. The latissimus dorsi and pectoralis major muscles exert a total force Fm on the arm. (a) Using the information in the figure, find the magnitude of the force Fm. (b) Suppose an athlete in training cannot perform the iron cross but can hold a position similar to the figure in which the arms make a 45 angle with the horizontal rather than being horizontal. Why is this position easier for the athlete? Figure P10.85arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning
Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
College Physics
Physics
ISBN:9781285737027
Author:Raymond A. Serway, Chris Vuille
Publisher:Cengage Learning
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
What is Torque? | Physics | Extraclass.com; Author: Extraclass Official;https://www.youtube.com/watch?v=zXxrAJld9mo;License: Standard YouTube License, CC-BY