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 39PE
Unreasonable Results
Suppose two children are using a uniform seesaw that is 3.00 m long and has its center of mass over the pivot. The first child has a mass of 30.0 kg and sits 1.40 m from the pivot. (a) Calculate where the second 18.0 kg child must sit to balance the seesaw. (b) What is unreasonable about the result? (c) Which premise is unreasonable, or which premises are inconsistent?
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
2, A seesaw in a children’s playground is 4.00 m long pivoted at its center. Suppose a 25-kg child sits at one end of the board, where should a 35-kg child sit to balance the seesaw?
A wooden plank is supported at two points as shown. What is the shortest distance from the end that a 80-kg person can stand without the other end lifting up? The plank is uniform, and its mass is 20.0 kg.
Even 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 support
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
6. (II) Vector is 6.6 using long and points along the negative x axis. Vector is 8.5 units long and points at t...
Physics: Principles with Applications
The electromagnetic spectrum of light is often arranged in terms of frequency. Which one of the following has t...
Lecture- Tutorials for Introductory Astronomy
2. A kidnapper demands a 40.0 kg cube of platinum as a ransom. What is the length of a side?
College Physics (10th Edition)
Carefully examine a bulb. Two wires extend from the filament of the bulb into the base. You probably cannot see...
Tutorials in Introductory Physics
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)
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
- What three factors affect the torque created by a force relative to a specific pivot point?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_forwardEven when the head is held erect, as in Figure 9.41, 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. (a) Calculate the force exerted by these muscles using the information in the figure. (b) What is the force exerted by the pivot on the head?arrow_forward
- Batman and Robin are lifting a 196 N uniform board with a length of 2.50 m. Batman exerts 55.0 N at a point 0.500 m from the left end. At what distance from left end of the board should Robin exert so that the board stays in equilibrium condition. (Hint: Use the two conditions for equilibrium in a rigid body)arrow_forwardTwo children sit on a seesaw. One has a mass of 30.0Kg and sits at 0.75m from the fulcrum to left. If the other child has a mass of 25.0 Kg, how far must he sit from the fulcrum to the right to balance the seesaw?arrow_forwardA trap door, of length and width 1.85 m, is held open at an angle of 65.0° with respect to the floor. A rope is attached to the raised edge of the door and fastened to the wall behind the door in such a position that the rope pulls perpendicularly to the trap door. If the mass of the trap door is 17.2 kg, what is the torque exerted on the trap door about the hinge by the rope? Enter a positive value if the torque is in counterclockwise direction and enter a negative value if the torque is in clockwise direction. ___N⋅marrow_forward
- True or False: If two forces of equal magnitude act on an object that is hinged at a pivot, the force acting farther from the pivot must produce the greater torque about the pivot.arrow_forwardYou push on the door as shown in the drawing. Calculate the torque experienced at the door hinge.arrow_forward
arrow_back_ios
arrow_forward_ios
Recommended textbooks for you
College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill
University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice University
College Physics
Physics
ISBN:9781938168000
Author:Paul Peter Urone, Roger Hinrichs
Publisher:OpenStax College
Glencoe Physics: Principles and Problems, Student...
Physics
ISBN:9780078807213
Author:Paul W. Zitzewitz
Publisher:Glencoe/McGraw-Hill
University Physics Volume 1
Physics
ISBN:9781938168277
Author:William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:OpenStax - Rice University
Static Equilibrium: concept; Author: Jennifer Cash;https://www.youtube.com/watch?v=0BIgFKVnlBU;License: Standard YouTube License, CC-BY