Your Comments. That s the plan

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Your Comments. That s the plan"

Transcription

1 Your Comments I love physics as much as the next gal, but I was wondering. Why don't we get class off the day after an evening exam? What if the ladder has friction with the wall? Things were complicated enough before adding rotation urgh!!!!!!!!! Please just cancel the 3rd exam and final and let's call it a semester!!! What exactly is a footprint? The pre-lecture made it seem like it was an intuitive concept, but what's the real definition? I really found this a difficult topic, except for the center of mass and stability. Please walk through an example or two so I can get the hang of this. As usual, I'm doing this pre-lecture after the exam, and my brain is totally fried. They help though. I may not be doing very well in this class, but I sure am learning a lot. This would be a good lecture to review all of the topics of rotations. I think a lot of people (myself included) have been focusing on the topics on the midterm and have neglected some of the new material That s the plan I have a weather related question. Sandy was a hurricane, but has transitioned into an extratropical cyclone, and an effect of this transition is that the storm has increased in size and (slightly) decreased in wind speed while central pressure has simultaneously decreased. Does conservation of momentum best explain why the storm has increased in size while winds have decreased? (rotation slows down about the central axis, so radius of rotation must increase) Possibly may also have to do with energy Mechanics Lecture 18, Slide 1

2 Since you asked.. I have heard the term center of gravity used, and it seems to be applicable here but it wasn't mentioned in the prelecture. Can you go over how the term center of gravity would be applied in the center of mass/footprint problems? Center of mass is the average position of stuff weighted by mass: X CM m x m x m m Center of gravity is the average position of stuff weighed by its weight: X CG w x w 1 2 w x... w... If weight can be written like w 1 =m 1 g then they are the same. If the strength of gravity varies across the object they can be different. We don t consider Center of Gravity in Physics 211 Mechanics Lecture 10, Slide 2

3 I have absolutely no idea how to do the "Three Masses" problem for the homework in section 16 that's due Friday. Could you please go over this in lecture, or at least give a hint on how to start it. T f m a 1 s fr a I s s s R s s T 1 T T 1 m a s T T R I 2 1 d d d a R s d 1 T T 2 1 m a d 2 f T 2 a m g 1 7 m m m 2 5 h h d s T 2 m h g m g T m a h 2 h

4 Physics 211 Lecture 18 Today s Concepts: a) Static Equilibrium b) Potential Energy & Stability Mechanics Lecture 18, Slide 4

5 Clicker Question A (static) mobile hangs as shown below. The rods are massless and have lengths as indicated. The mass of the ball at the bottom right is 1 kg. What is the total mass of the mobile? A) 4 kg B) 5 kg C) 6 kg D) 7 kg E) 8 kg 1 m 2 m 1 m 3 m 1 kg Mechanics Lecture 18, Slide 5

6 Clicker Question In which of the static cases shown below is the tension in the supporting wire bigger? In both cases M is the same, and the blue strut is massless. A) Case 1 B) Case 2 C) Same T T M L M L/2 Case 1 Case 2 Mechanics Lecture 18, Slide 6

7 It s the same. Why? Case 1 Case 2 T 1 q d 1 T 2 d 2 q M L M L/2 Balancing Torques L L MgL T L sin q 0 1 Mg T sin T 1 Mg sin q T 2 Mg sin q Mechanics Lecture 18, Slide 7

8 CheckPoint In which of the static cases shown below is the tension in the supporting wire bigger? In both cases the red strut has the same mass and length. A) Case 1 B) Case 2 C) Same T 1 T M L Case 1 L/2 Case 2 Mechanics Lecture 18, Slide 8

9 CheckPoint In which of the static cases shown below is the tension in the supporting wire bigger? In both cases the red strut has the same mass and length. A) Case 1 B) Case 2 C) Same A) the length is longer. B) Both strings have to provide an equal torque to hold the beam. In case 2, the perpendicular distance from the pivot is less which means a greater force is needed to hold the beam up. C) the center of mass for the rod is the same in both cases. therefore the force due to gravity is the same. to be static, the tension must equal of gravity, therefore tension force is the same. Mechanics Lecture 18, Slide 9

10 Homework Problem T 1 T 2 Same distance from CM: T 1 T 2 T CM Balance forces: T 1 T 2 Mg So: T Mg/2 Mg Mechanics Lecture 18, Slide 10

11 Homework Problem Mechanics Lecture 18, Slide 11

12 These are the quantities we want to find: T 1 A CM M d Mg y x Mechanics Lecture 18, Slide 12

13 Clicker Question What is the moment of inertia of the beam about the rotation axis shown by the blue dot? A) B) I I 1 12 M d M L 2 2 d L M C) 1 I M L M d Mechanics Lecture 18, Slide 13

14 Clicker Question The center of mass of the beam accelerates downward. Use this fact to figure out how T 1 compares to weight of the beam? A) T 1 Mg T 1 A CM M B) T 1 > Mg d C) T 1 < Mg Mg y x Mechanics Lecture 18, Slide 14

15 Clicker Question The center of mass of the beam accelerates downward. How is this acceleration related to the angular acceleration of the beam? A) A CM d T 1 A CM M B) A CM d / d C) A CM / d Mg y x Mechanics Lecture 18, Slide 15

16 Apply F ext M A C M A CM d Mg T MA 1 CM T Mg MA 1 CM T 1 A CM M Apply I ext d M gd I I A CM d Mg y A CM g Md I 2 Use A CM d to find x Plug this into the expression for T 1 Mechanics Lecture 18, Slide 16

17 After the right string is cut, the meterstick swings down to where it is vertical for an instant before it swings back up in the other direction. What is the angular speed when the meter stick is vertical? Conserve energy: 1 M gd 2 I 2 M gd I 2 T d M y x CM demos Mechanics Lecture 18, Slide 17

18 Applying F ext M A C M T T Mg M d 2 Centripetal acceleration T Mg M d 2 d A CM 2 d y Mg x Mechanics Lecture 18, Slide 18

19 Another HW problem: We will now work out the general case Mechanics Lecture 18, Slide 19

20 General Case of a Person on a Ladder Bill (mass m) is climbing a ladder (length L, mass M) that leans against a smooth wall (no friction between wall and ladder). A frictional force f between the ladder and the floor keeps it from slipping. The angle between the ladder and the wall is f. How does f depend on the angle of the ladder and Bill s distance up the ladder? Bill m L M f y x f q Mechanics Lecture 18, Slide 20

21 Balance forces: x: F wall f y: N Mg mg Balance torques: L mgd cos q Mg cos 2 q F Lsin q 0 wall L/2 F wall F wall mg d L Fwall Mg cot 2 q d M g f m g cot q L 2 f axis f N d q mg Mg y x Mechanics Lecture 18, Slide 21

22 This is the General Expression: d M g f m g cot q L 2 Climbing further up the ladder makes it more likely to slip: Making the ladder more vertical makes it less likely to slip: M d m Lets try it out f q Mechanics Lecture 18, Slide 22

23 If its just a ladder d M g f m g cot q L 2 f Mg 2 cot q Moving the bottom of the ladder further from the wall makes it more likely to slip: Mechanics Lecture 18, Slide 23

24 CheckPoint In the two cases shown below identical ladders are leaning against frictionless walls. In which case is the force of friction between the ladder and the ground the biggest? A) Case 1 B) Case 2 C) Same Case 1 Case 2 Mechanics Lecture 18, Slide 24

25 CheckPoint In the two cases shown below identical ladders are leaning against frictionless walls. In which case is the force of friction between the ladder and the ground the biggest? A) Case 1 B) Case 2 C) Same A) The ladder is most likely to slip when theta is increased so by this logic, when the angle is greater, the force of friction must also be greater. Case 1 Case 2 B) In Case 2, the ladder is more vertical and pushes against the ground more, causing there to be a greater normal force. Friction is a constant times this normal force. Mechanics Lecture 18, Slide 25

26 CheckPoint Suppose you hang one end of a beam from the ceiling by a rope and the bottom of the beam rests on a frictionless sheet of ice. The center of mass of the beam is marked with an black spot. Which of the following configurations best represents the equilibrium condition of this setup? A) B) C) Mechanics Lecture 18, Slide 26

27 CheckPoint Which of the following configurations best represents the equilibrium condition of this setup? A) B) C) B) Center of mass of the beam is directly beneath the axis of rotation of the rope. C) The center of mass is lowest in C, minimizing gravitational potential energy. Mechanics Lecture 18, Slide 27

28 Stability & Potential Energy I don't understand what is meant by 'inside the footprint'. footprint footprint Mechanics Lecture 18, Slide 28

Announcements Oct 16, 2014

Announcements Oct 16, 2014 Announcements Oct 16, 2014 1. Prayer 2. While waiting, see how many of these blanks you can fill out: Centripetal Accel.: Causes change in It points but not Magnitude: a c = How to use with N2: Always

More information

Chapter 11. Today. Last Wednesday. Precession from Pre- lecture. Solving problems with torque

Chapter 11. Today. Last Wednesday. Precession from Pre- lecture. Solving problems with torque Chapter 11 Last Wednesday Solving problems with torque Work and power with torque Angular momentum Conserva5on of angular momentum Today Precession from Pre- lecture Study the condi5ons for equilibrium

More information

Physics 2210 Homework 18 Spring 2015

Physics 2210 Homework 18 Spring 2015 Physics 2210 Homework 18 Spring 2015 Charles Jui April 12, 2015 IE Sphere Incline Wording A solid sphere of uniform density starts from rest and rolls without slipping down an inclined plane with angle

More information

Last 6 lectures are easier

Last 6 lectures are easier Your Comments I love you. Seriously. I do. And you never post it. I felt really bad whilst completing the checkpoint for this. This stuff is way above my head and I struggled with the concept of precession.

More information

Physics 101: Lecture 15 Torque, F=ma for rotation, and Equilibrium

Physics 101: Lecture 15 Torque, F=ma for rotation, and Equilibrium Physics 101: Lecture 15 Torque, F=ma for rotation, and Equilibrium Strike (Day 10) Prelectures, checkpoints, lectures continue with no change. Take-home quizzes this week. See Elaine Schulte s email. HW

More information

Equilibrium & Elasticity

Equilibrium & Elasticity PHYS 101 Previous Exam Problems CHAPTER 12 Equilibrium & Elasticity Static equilibrium Elasticity 1. A uniform steel bar of length 3.0 m and weight 20 N rests on two supports (A and B) at its ends. A block

More information

PHYSICS 149: Lecture 21

PHYSICS 149: Lecture 21 PHYSICS 149: Lecture 21 Chapter 8: Torque and Angular Momentum 8.2 Torque 8.4 Equilibrium Revisited 8.8 Angular Momentum Lecture 21 Purdue University, Physics 149 1 Midterm Exam 2 Wednesday, April 6, 6:30

More information

Applying Newton s Laws

Applying Newton s Laws Chapter 5 Applying Newton s Laws PowerPoint Lectures for University Physics, Twelfth Edition Hugh D. Young and Roger A. Freedman Lectures by James Pazun Goals for Chapter 5 To use and apply Newton s Laws

More information

Phys 1401: General Physics I

Phys 1401: General Physics I 1. (0 Points) What course is this? a. PHYS 1401 b. PHYS 1402 c. PHYS 2425 d. PHYS 2426 2. (0 Points) Which exam is this? a. Exam 1 b. Exam 2 c. Final Exam 3. (0 Points) What version of the exam is this?

More information

Physics 211 Week 10. Statics: Walking the Plank (Solution)

Physics 211 Week 10. Statics: Walking the Plank (Solution) Statics: Walking the Plank (Solution) A uniform horizontal beam 8 m long is attached by a frictionless pivot to a wall. A cable making an angle of 37 o, attached to the beam 5 m from the pivot point, supports

More information

Chapter 4: Newton s Second Law F = m a. F = m a (4.2)

Chapter 4: Newton s Second Law F = m a. F = m a (4.2) Lecture 7: Newton s Laws and Their Applications 1 Chapter 4: Newton s Second Law F = m a First Law: The Law of Inertia An object at rest will remain at rest unless, until acted upon by an external force.

More information

PHY218 SPRING 2016 Review for Final Exam: Week 14 Final Review: Chapters 1-11, 13-14

PHY218 SPRING 2016 Review for Final Exam: Week 14 Final Review: Chapters 1-11, 13-14 Final Review: Chapters 1-11, 13-14 These are selected problems that you are to solve independently or in a team of 2-3 in order to better prepare for your Final Exam 1 Problem 1: Chasing a motorist This

More information

Announcements. Civil and Mechanical engineers: This week is for you!

Announcements. Civil and Mechanical engineers: This week is for you! Announcements Civil and echanical engineers: his week is for you! Ø Sta;cs: Oooh, so exci;ng! Ø Please pay aaen;on: We want you to build bridges that don t fall down! Exam 3 next Wednesday!!! (November

More information

11. (7 points: Choose up to 3 answers) What is the tension,!, in the string? a.! = 0.10 N b.! = 0.21 N c.! = 0.29 N d.! = N e.! = 0.

11. (7 points: Choose up to 3 answers) What is the tension,!, in the string? a.! = 0.10 N b.! = 0.21 N c.! = 0.29 N d.! = N e.! = 0. A harmonic wave propagates horizontally along a taut string of length! = 8.0 m and mass! = 0.23 kg. The vertical displacement of the string along its length is given by!!,! = 0.1!m cos 1.5!!! +!0.8!!,

More information

Chapter 9: Rotational Dynamics Tuesday, September 17, 2013

Chapter 9: Rotational Dynamics Tuesday, September 17, 2013 Chapter 9: Rotational Dynamics Tuesday, September 17, 2013 10:00 PM The fundamental idea of Newtonian dynamics is that "things happen for a reason;" to be more specific, there is no need to explain rest

More information

Your Comments. Mechanics Lecture 19, Slide 1

Your Comments. Mechanics Lecture 19, Slide 1 Your Comments i studied so hard for exam... and i did so bad :'( why physics u no love me. When we say a system will conserve angular momentum, does the solar system count? Say the sun suddenly expands

More information

AP Physics Multiple Choice Practice Torque

AP Physics Multiple Choice Practice Torque AP Physics Multiple Choice Practice Torque 1. A uniform meterstick of mass 0.20 kg is pivoted at the 40 cm mark. Where should one hang a mass of 0.50 kg to balance the stick? (A) 16 cm (B) 36 cm (C) 44

More information

Summer Physics 41 Pretest. Shorty Shorts (2 pts ea): Circle the best answer. Show work if a calculation is required.

Summer Physics 41 Pretest. Shorty Shorts (2 pts ea): Circle the best answer. Show work if a calculation is required. Summer Physics 41 Pretest Name: Shorty Shorts (2 pts ea): Circle the best answer. Show work if a calculation is required. 1. An object hangs in equilibrium suspended by two identical ropes. Which rope

More information

Exam 3 Practice Solutions

Exam 3 Practice Solutions Exam 3 Practice Solutions Multiple Choice 1. A thin hoop, a solid disk, and a solid sphere, each with the same mass and radius, are at rest at the top of an inclined plane. If all three are released at

More information

Practice Problems from Chapters 11-13, for Midterm 2. Physics 11a Fall 2010

Practice Problems from Chapters 11-13, for Midterm 2. Physics 11a Fall 2010 Practice Problems from Chapters 11-13, for Midterm 2. Physics 11a Fall 2010 Chapter 11 1. The Ferris wheel shown below is turning at constant speed. Draw and label free-body diagrams showing the forces

More information

Name Date Period PROBLEM SET: ROTATIONAL DYNAMICS

Name Date Period PROBLEM SET: ROTATIONAL DYNAMICS Accelerated Physics Rotational Dynamics Problem Set Page 1 of 5 Name Date Period PROBLEM SET: ROTATIONAL DYNAMICS Directions: Show all work on a separate piece of paper. Box your final answer. Don t forget

More information

Static Equilibrium. Lecture 22. Chapter 12. Physics I Department of Physics and Applied Physics

Static Equilibrium. Lecture 22. Chapter 12. Physics I Department of Physics and Applied Physics Lecture 22 Chapter 12 Physics I 12.02.2013 Static Equilibrium Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsi Lecture Capture: http://echo360.uml.edu/danylov2013/physics1fall.html

More information

Chapter 9 Rotational Dynamics

Chapter 9 Rotational Dynamics Chapter 9 ROTATIONAL DYNAMICS PREVIEW A force acting at a perpendicular distance from a rotation point, such as pushing a doorknob and causing the door to rotate on its hinges, produces a torque. If the

More information

Newton and Real Life. Newton and Real Life 9/13/12. Friction, Springs and Scales. Summary

Newton and Real Life. Newton and Real Life 9/13/12. Friction, Springs and Scales. Summary Friction, s and Scales Summary Last Net force - Terminal velocity (- Car Crashes) Day 6: Friction s Where shoes make a difference Reminders: Homework 3 due Monday No HW or new reading net week! Review

More information

I pt mass = mr 2 I sphere = (2/5) mr 2 I hoop = mr 2 I disk = (1/2) mr 2 I rod (center) = (1/12) ml 2 I rod (end) = (1/3) ml 2

I pt mass = mr 2 I sphere = (2/5) mr 2 I hoop = mr 2 I disk = (1/2) mr 2 I rod (center) = (1/12) ml 2 I rod (end) = (1/3) ml 2 Fall 008 RED Barcode Here Physics 105, sections 1 and Exam 3 Please write your CID Colton -3669 3 hour time limit. One 3 5 handwritten note card permitted (both sides). Calculators permitted. No books.

More information

Static Equilibrium. Lecture 24. Chapter 12. Physics I. Department of Physics and Applied Physics

Static Equilibrium. Lecture 24. Chapter 12. Physics I. Department of Physics and Applied Physics Lecture 24 Chapter 12 Physics I Static Equilibrium Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsi IN THIS CHAPTER, you will discuss static equilibrium of an object Today we are

More information

Chapter 6, Problem 18. Agenda. Rotational Inertia. Rotational Inertia. Calculating Moment of Inertia. Example: Hoop vs.

Chapter 6, Problem 18. Agenda. Rotational Inertia. Rotational Inertia. Calculating Moment of Inertia. Example: Hoop vs. Agenda Today: Homework quiz, moment of inertia and torque Thursday: Statics problems revisited, rolling motion Reading: Start Chapter 8 in the reading Have to cancel office hours today: will have extra

More information

Consider two students pushing with equal force on opposite sides of a desk. Looking top-down on the desk:

Consider two students pushing with equal force on opposite sides of a desk. Looking top-down on the desk: 1 Bodies in Equilibrium Recall Newton's First Law: if there is no unbalanced force on a body (i.e. if F Net = 0), the body is in equilibrium. That is, if a body is in equilibrium, then all the forces on

More information

Upthrust and Archimedes Principle

Upthrust and Archimedes Principle 1 Upthrust and Archimedes Principle Objects immersed in fluids, experience a force which tends to push them towards the surface of the liquid. This force is called upthrust and it depends on the density

More information

Torque. Physics 6A. Prepared by Vince Zaccone For Campus Learning Assistance Services at UCSB

Torque. Physics 6A. Prepared by Vince Zaccone For Campus Learning Assistance Services at UCSB Physics 6A Torque is what causes angular acceleration (just like a force causes linear acceleration) Torque is what causes angular acceleration (just like a force causes linear acceleration) For a torque

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) You are standing in a moving bus, facing forward, and you suddenly fall forward as the

More information

Physics 218 Exam III

Physics 218 Exam III Physics 218 Exam III Spring 2017 (all sections) April 17 th, 2017 Rules of the exam: Please fill out the information and read the instructions below, but do not open the exam until told to do so. 1. You

More information

= y(x, t) =A cos (!t + kx)

= y(x, t) =A cos (!t + kx) A harmonic wave propagates horizontally along a taut string of length L = 8.0 m and mass M = 0.23 kg. The vertical displacement of the string along its length is given by y(x, t) = 0. m cos(.5 t + 0.8

More information

Bryant Grigsby (Physics BSc) Vice President of Operations and New Product Introduction Lumenetix Scotts Valley, CA

Bryant Grigsby (Physics BSc) Vice President of Operations and New Product Introduction Lumenetix Scotts Valley, CA PHYSICIST PROFILE Bryant Grigsby (Physics BSc) Vice President of Operations and New Product Introduction Lumenetix Scotts Valley, CA Bryant first considered a business major but found it lacking in technical

More information

Review PHYS114 Chapters 4-7

Review PHYS114 Chapters 4-7 Review PHYS114 Chapters 4-7 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A 27 kg object is accelerated at a rate of 1.7 m/s 2. What force does

More information

Stuff you asked about:

Stuff you asked about: Stuff you asked about: Instrumental illness Can you go over the change in momentum with respect to the change in time being used to calcuate the net force in depth more during the lecture. We never really

More information

Physics 131: Lecture 21. Today s Agenda

Physics 131: Lecture 21. Today s Agenda Physics 131: Lecture 21 Today s Agenda Rotational dynamics Torque = I Angular Momentum Physics 201: Lecture 10, Pg 1 Newton s second law in rotation land Sum of the torques will equal the moment of inertia

More information

Name Section Number Team Number

Name Section Number Team Number Physics 218 LAB: TORQUES and STATIC EQUILIBRIUM Name Section Number Team Number Introduction One purpose of this lab is to introduce you to quantity called torque or, as engineers cail it, moment of a

More information

= o + t = ot + ½ t 2 = o + 2

= o + t = ot + ½ t 2 = o + 2 Chapters 8-9 Rotational Kinematics and Dynamics Rotational motion Rotational motion refers to the motion of an object or system that spins about an axis. The axis of rotation is the line about which the

More information

TEST REPORT. Question file: P Copyright:

TEST REPORT. Question file: P Copyright: Date: February-12-16 Time: 2:00:28 PM TEST REPORT Question file: P12-2006 Copyright: Test Date: 21/10/2010 Test Name: EquilibriumPractice Test Form: 0 Test Version: 0 Test Points: 138.00 Test File: EquilibriumPractice

More information

Torque and Static Equilibrium

Torque and Static Equilibrium Torque and Static Equilibrium Rigid Bodies Rigid body: An extended object in which the distance between any two points in the object is constant in time. Examples: sphere, disk Effect of external forces

More information

Name Student ID Score Last First. I = 2mR 2 /5 around the sphere s center of mass?

Name Student ID Score Last First. I = 2mR 2 /5 around the sphere s center of mass? NOTE: ignore air resistance in all Questions. In all Questions choose the answer that is the closest!! Question I. (15 pts) Rotation 1. (5 pts) A bowling ball that has an 11 cm radius and a 7.2 kg mass

More information

Physics 53 Exam 3 November 3, 2010 Dr. Alward

Physics 53 Exam 3 November 3, 2010 Dr. Alward 1. When the speed of a rear-drive car (a car that's driven forward by the rear wheels alone) is increasing on a horizontal road the direction of the frictional force on the tires is: A) forward for all

More information

Mechanics II. Which of the following relations among the forces W, k, N, and F must be true?

Mechanics II. Which of the following relations among the forces W, k, N, and F must be true? Mechanics II 1. By applying a force F on a block, a person pulls a block along a rough surface at constant velocity v (see Figure below; directions, but not necessarily magnitudes, are indicated). Which

More information

We define angular displacement, θ, and angular velocity, ω. What's a radian?

We define angular displacement, θ, and angular velocity, ω. What's a radian? We define angular displacement, θ, and angular velocity, ω Units: θ = rad ω = rad/s What's a radian? Radian is the ratio between the length of an arc and its radius note: counterclockwise is + clockwise

More information

Newton s Law of Motion

Newton s Law of Motion Newton s Law of Motion Physics 211 Syracuse University, Physics 211 Spring 2017 Walter Freeman February 13, 2017 W. Freeman Newton s Law of Motion February 13, 2017 1 / 21 Announcements Homework 3 due

More information

Angular Momentum L = I ω

Angular Momentum L = I ω Angular Momentum L = Iω If no NET external Torques act on a system then Angular Momentum is Conserved. Linitial = I ω = L final = Iω Angular Momentum L = Iω Angular Momentum L = I ω A Skater spins with

More information

PHY131H1F - Class 9. Today, finishing Chapter 5: Kinetic Friction Static Friction Rolling without slipping (intro) Drag

PHY131H1F - Class 9. Today, finishing Chapter 5: Kinetic Friction Static Friction Rolling without slipping (intro) Drag PHY131H1F - Class 9 Today, finishing Chapter 5: Kinetic Friction Static Friction Rolling without slipping (intro) Drag Microscopic bumps and holes crash into each other, causing a frictional force. Kinetic

More information

Chapter 8, Rotational Equilibrium and Rotational Dynamics. 3. If a net torque is applied to an object, that object will experience:

Chapter 8, Rotational Equilibrium and Rotational Dynamics. 3. If a net torque is applied to an object, that object will experience: CHAPTER 8 3. If a net torque is applied to an object, that object will experience: a. a constant angular speed b. an angular acceleration c. a constant moment of inertia d. an increasing moment of inertia

More information

Newton s 3 Laws of Motion

Newton s 3 Laws of Motion Newton s 3 Laws of Motion 1. If F = 0 No change in motion 2. = ma Change in motion Fnet 3. F = F 1 on 2 2 on 1 Newton s First Law (Law of Inertia) An object will remain at rest or in a constant state of

More information

PHYS 1303 Final Exam Example Questions

PHYS 1303 Final Exam Example Questions PHYS 1303 Final Exam Example Questions (In summer 2014 we have not covered questions 30-35,40,41) 1.Which quantity can be converted from the English system to the metric system by the conversion factor

More information

The Laws of Motion. Newton s first law Force Mass Newton s second law Gravitational Force Newton s third law Examples

The Laws of Motion. Newton s first law Force Mass Newton s second law Gravitational Force Newton s third law Examples The Laws of Motion Newton s first law Force Mass Newton s second law Gravitational Force Newton s third law Examples Gravitational Force Gravitational force is a vector Expressed by Newton s Law of Universal

More information

Assignments VIII and IX, PHYS 301 (Classical Mechanics) Spring 2014 Due 3/21/14 at start of class

Assignments VIII and IX, PHYS 301 (Classical Mechanics) Spring 2014 Due 3/21/14 at start of class Assignments VIII and IX, PHYS 301 (Classical Mechanics) Spring 2014 Due 3/21/14 at start of class Homeworks VIII and IX both center on Lagrangian mechanics and involve many of the same skills. Therefore,

More information

Physics 131: Lecture 21. Today s Agenda

Physics 131: Lecture 21. Today s Agenda Physics 131: Lecture 1 Today s Agenda Rotational dynamics Torque = I Angular Momentum Physics 01: Lecture 10, Pg 1 Newton s second law in rotation land Sum of the torques will equal the moment of inertia

More information

Static Equilibrium; Torque

Static Equilibrium; Torque Static Equilibrium; Torque The Conditions for Equilibrium An object with forces acting on it, but that is not moving, is said to be in equilibrium. The first condition for equilibrium is that the net force

More information

Concept Question: Normal Force

Concept Question: Normal Force Concept Question: Normal Force Consider a person standing in an elevator that is accelerating upward. The upward normal force N exerted by the elevator floor on the person is 1. larger than 2. identical

More information

Physics 8 Wednesday, October 14, 2015

Physics 8 Wednesday, October 14, 2015 Physics 8 Wednesday, October 14, 2015 HW5 due Friday (problems from Ch9 and Ch10.) Bill/Camilla switch HW sessions this week only (same rooms, same times what changes is which one of us is there): Weds

More information

Solution Derivations for Capa #12

Solution Derivations for Capa #12 Solution Derivations for Capa #12 1) A hoop of radius 0.200 m and mass 0.460 kg, is suspended by a point on it s perimeter as shown in the figure. If the hoop is allowed to oscillate side to side as a

More information

Angular Momentum L = I ω

Angular Momentum L = I ω Angular Momentum L = Iω If no NET external Torques act on a system then Angular Momentum is Conserved. Linitial = I ω = L final = Iω Angular Momentum L = Iω Angular Momentum L = I ω A Skater spins with

More information

Torque. Introduction. Torque. PHY torque - J. Hedberg

Torque. Introduction. Torque. PHY torque - J. Hedberg Torque PHY 207 - torque - J. Hedberg - 2017 1. Introduction 2. Torque 1. Lever arm changes 3. Net Torques 4. Moment of Rotational Inertia 1. Moment of Inertia for Arbitrary Shapes 2. Parallel Axis Theorem

More information

PHYS 101 Previous Exam Problems. Force & Motion I

PHYS 101 Previous Exam Problems. Force & Motion I PHYS 101 Previous Exam Problems CHAPTER 5 Force & Motion I Newton s Laws Vertical motion Horizontal motion Mixed forces Contact forces Inclines General problems 1. A 5.0-kg block is lowered with a downward

More information

III. Angular Momentum Conservation (Chap. 10) Rotation. We repeat Chap. 2-8 with rotatiing objects. Eqs. of motion. Energy.

III. Angular Momentum Conservation (Chap. 10) Rotation. We repeat Chap. 2-8 with rotatiing objects. Eqs. of motion. Energy. Chap. 10: Rotational Motion I. Rotational Kinematics II. Rotational Dynamics - Newton s Law for Rotation III. Angular Momentum Conservation (Chap. 10) 1 Toward Exam 3 Eqs. of motion o To study angular

More information

Solution Only gravity is doing work. Since gravity is a conservative force mechanical energy is conserved:

Solution Only gravity is doing work. Since gravity is a conservative force mechanical energy is conserved: 8) roller coaster starts with a speed of 8.0 m/s at a point 45 m above the bottom of a dip (see figure). Neglecting friction, what will be the speed of the roller coaster at the top of the next slope,

More information

Part A Atwood Machines Please try this link:

Part A Atwood Machines Please try this link: LAST NAME FIRST NAME DATE Assignment 2 Inclined Planes, Pulleys and Accelerating Fluids Problems 83, 108 & 109 (and some handouts) Part A Atwood Machines Please try this link: http://www.wiley.com/college/halliday/0470469080/simulations/sim20/sim20.html

More information

Rotational Kinetic Energy

Rotational Kinetic Energy Lecture 17, Chapter 10: Rotational Energy and Angular Momentum 1 Rotational Kinetic Energy Consider a rigid body rotating with an angular velocity ω about an axis. Clearly every point in the rigid body

More information

Physics Mechanics. Lecture 11 Newton s Laws - part 2

Physics Mechanics. Lecture 11 Newton s Laws - part 2 Physics 170 - Mechanics Lecture 11 Newton s Laws - part 2 Newton s Second Law of Motion An object may have several forces acting on it; the acceleration is due to the net force: Newton s Second Law of

More information

Page 1. Chapters 2, 3 (linear) 9 (rotational) Final Exam: Wednesday, May 11, 10:05 am - 12:05 pm, BASCOM 272

Page 1. Chapters 2, 3 (linear) 9 (rotational) Final Exam: Wednesday, May 11, 10:05 am - 12:05 pm, BASCOM 272 Final Exam: Wednesday, May 11, 10:05 am - 12:05 pm, BASCOM 272 The exam will cover chapters 1 14 The exam will have about 30 multiple choice questions Consultations hours the same as before. Another review

More information

Which, if any, of the velocity versus time graphs below represent the movement of the sliding box?

Which, if any, of the velocity versus time graphs below represent the movement of the sliding box? Review Packet Name: _ 1. A box is sliding to the right along a horizontal surface with a velocity of 2 m/s. There is friction between the box and the horizontal surface. The box is tied to a hanging stone

More information

Exam 3 PREP Chapters 6, 7, 8

Exam 3 PREP Chapters 6, 7, 8 PHY241 - General Physics I Dr. Carlson, Fall 2013 Prep Exam 3 PREP Chapters 6, 7, 8 Name TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) Astronauts in orbiting satellites

More information

Torque rotational force which causes a change in rotational motion. This force is defined by linear force multiplied by a radius.

Torque rotational force which causes a change in rotational motion. This force is defined by linear force multiplied by a radius. Warm up A remote-controlled car's wheel accelerates at 22.4 rad/s 2. If the wheel begins with an angular speed of 10.8 rad/s, what is the wheel's angular speed after exactly three full turns? AP Physics

More information

CHAPTER 8: ROTATIONAL OF RIGID BODY PHYSICS. 1. Define Torque

CHAPTER 8: ROTATIONAL OF RIGID BODY PHYSICS. 1. Define Torque 7 1. Define Torque 2. State the conditions for equilibrium of rigid body (Hint: 2 conditions) 3. Define angular displacement 4. Define average angular velocity 5. Define instantaneous angular velocity

More information

Practice Test 3. Name: Date: ID: A. Multiple Choice Identify the choice that best completes the statement or answers the question.

Practice Test 3. Name: Date: ID: A. Multiple Choice Identify the choice that best completes the statement or answers the question. Name: Date: _ Practice Test 3 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A wheel rotates about a fixed axis with an initial angular velocity of 20

More information

Angular Speed and Angular Acceleration Relations between Angular and Linear Quantities

Angular Speed and Angular Acceleration Relations between Angular and Linear Quantities Angular Speed and Angular Acceleration Relations between Angular and Linear Quantities 1. The tires on a new compact car have a diameter of 2.0 ft and are warranted for 60 000 miles. (a) Determine the

More information

Physics 111 Lecture 4 Newton`s Laws

Physics 111 Lecture 4 Newton`s Laws Physics 111 Lecture 4 Newton`s Laws Dr. Ali ÖVGÜN EMU Physics Department www.aovgun.com he Laws of Motion q Newton s first law q Force q Mass q Newton s second law q Newton s third law q Examples Isaac

More information

FALL TERM EXAM, PHYS 1211, INTRODUCTORY PHYSICS I Saturday, 14 December 2013, 1PM to 4 PM, AT 1003

FALL TERM EXAM, PHYS 1211, INTRODUCTORY PHYSICS I Saturday, 14 December 2013, 1PM to 4 PM, AT 1003 FALL TERM EXAM, PHYS 1211, INTRODUCTORY PHYSICS I Saturday, 14 December 2013, 1PM to 4 PM, AT 1003 NAME: STUDENT ID: INSTRUCTION 1. This exam booklet has 14 pages. Make sure none are missing 2. There is

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A 4.8-kg block attached to a spring executes simple harmonic motion on a frictionless

More information

UNIVERSITY OF MANITOBA. All questions are of equal value. Answer all questions. No marks are subtracted for wrong answers.

UNIVERSITY OF MANITOBA. All questions are of equal value. Answer all questions. No marks are subtracted for wrong answers. PAGE NO.: 1 of 5 All questions are of equal value. Answer all questions. No marks are subtracted for wrong answers. Record all answers on the computer score sheet provided. USE PENCIL ONLY! Black pen will

More information

Two Hanging Masses. ) by considering just the forces that act on it. Use Newton's 2nd law while

Two Hanging Masses. ) by considering just the forces that act on it. Use Newton's 2nd law while Student View Summary View Diagnostics View Print View with Answers Edit Assignment Settings per Student Exam 2 - Forces [ Print ] Due: 11:59pm on Tuesday, November 1, 2011 Note: To underst how points are

More information

Chapter 8 Rotational Motion and Equilibrium. 1. Give explanation of torque in own words after doing balance-the-torques lab as an inquiry introduction

Chapter 8 Rotational Motion and Equilibrium. 1. Give explanation of torque in own words after doing balance-the-torques lab as an inquiry introduction Chapter 8 Rotational Motion and Equilibrium Name 1. Give explanation of torque in own words after doing balance-the-torques lab as an inquiry introduction 1. The distance between a turning axis and the

More information

Chapter 7 Newton s Third Law

Chapter 7 Newton s Third Law Chapter 7 Newton s Third Law Chapter Goal: To use Newton s third law to understand interacting objects. Slide 7-2 Chapter 7 Preview Slide 7-3 Chapter 7 Preview Slide 7-4 Chapter 7 Preview Slide 7-6 Chapter

More information

PHY131H1S - Class 20. Pre-class reading quiz on Chapter 12

PHY131H1S - Class 20. Pre-class reading quiz on Chapter 12 PHY131H1S - Class 20 Today: Gravitational Torque Rotational Kinetic Energy Rolling without Slipping Equilibrium with Rotation Rotation Vectors Angular Momentum Pre-class reading quiz on Chapter 12 1 Last

More information

Rotational N.2 nd Law

Rotational N.2 nd Law Lecture 0 Chapter 1 Physics I Rotational N. nd Law Torque Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsi IN THIS CHAPTER, you will continue discussing rotational dynamics Today

More information

Q16.: A 5.0 kg block is lowered with a downward acceleration of 2.8 m/s 2 by means of a rope. The force of the block on the rope is:(35 N, down)

Q16.: A 5.0 kg block is lowered with a downward acceleration of 2.8 m/s 2 by means of a rope. The force of the block on the rope is:(35 N, down) Old Exam Question Ch. 5 T072 Q13.Two blocks of mass m 1 = 24.0 kg and m 2, respectively, are connected by a light string that passes over a massless pulley as shown in Fig. 2. If the tension in the string

More information

PHYSICS 231 Laws of motion PHY 231

PHYSICS 231 Laws of motion PHY 231 PHYSICS 231 Laws of motion 1 Newton s Laws First Law: If the net force exerted on an object is zero the object continues in its original state of motion; if it was at rest, it remains at rest. If it was

More information

PHY 111L Activity 9 Moments of Inertia

PHY 111L Activity 9 Moments of Inertia PHY 111L Activity 9 Moments of Inertia Name: Section: ID #: Date: Lab Partners: TA initials: Objectives 1. Introduce moment of inertia for different objects 2. Understand the moment of inertia apparatus

More information

MITOCW free_body_diagrams

MITOCW free_body_diagrams MITOCW free_body_diagrams This is a bungee jumper at the bottom of his trajectory. This is a pack of dogs pulling a sled. And this is a golf ball about to be struck. All of these scenarios can be represented

More information

Lecture 11 - Advanced Rotational Dynamics

Lecture 11 - Advanced Rotational Dynamics Lecture 11 - Advanced Rotational Dynamics A Puzzle... A moldable blob of matter of mass M and uniform density is to be situated between the planes z = 0 and z = 1 so that the moment of inertia around the

More information

Lecture 6 Force and Motion. Identifying Forces Free-body Diagram Newton s Second Law

Lecture 6 Force and Motion. Identifying Forces Free-body Diagram Newton s Second Law Lecture 6 Force and Motion Identifying Forces Free-body Diagram Newton s Second Law We are now moving on from the study of motion to studying what causes motion. Forces are what cause motion. Forces are

More information

Work and kinetic Energy

Work and kinetic Energy Work and kinetic Energy Problem 66. M=4.5kg r = 0.05m I = 0.003kgm 2 Q: What is the velocity of mass m after it dropped a distance h? (No friction) h m=0.6kg mg Work and kinetic Energy Problem 66. M=4.5kg

More information

Chapter 12. Rotation of a Rigid Body

Chapter 12. Rotation of a Rigid Body Chapter 12. Rotation of a Rigid Body Not all motion can be described as that of a particle. Rotation requires the idea of an extended object. This diver is moving toward the water along a parabolic trajectory,

More information

End-of-Chapter Exercises

End-of-Chapter Exercises End-of-Chapter Exercises Exercises 1 12 are conceptual questions that are designed to see if you have understood the main concepts of the chapter. 1. When a spring is compressed 10 cm, compared to its

More information

Fall 2007 RED Barcode Here Physics 105, sections 1 and 2 Please write your CID Colton

Fall 2007 RED Barcode Here Physics 105, sections 1 and 2 Please write your CID Colton Fall 007 RED Barcode Here Physics 105, sections 1 and Exam 3 Please write your CID Colton -3669 3 hour time limit. One 3 5 handwritten note card permitted (both sides). Calculators permitted. No books.

More information

Physics 207 Lecture 10. Lecture 10. Employ Newton s Laws in 2D problems with circular motion

Physics 207 Lecture 10. Lecture 10. Employ Newton s Laws in 2D problems with circular motion Lecture 10 Goals: Employ Newton s Laws in 2D problems with circular motion Assignment: HW5, (Chapters 8 & 9, due 3/4, Wednesday) For Tuesday: Finish reading Chapter 8, start Chapter 9. Physics 207: Lecture

More information

PHYSICS. Chapter 5 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT Pearson Education, Inc.

PHYSICS. Chapter 5 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT Pearson Education, Inc. PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 5 Lecture RANDALL D. KNIGHT Chapter 5 Force and Motion IN THIS CHAPTER, you will learn about the connection between force and motion.

More information

Tue Sept 15. Dynamics - Newton s Laws of Motion. Forces: Identifying Forces Free-body diagram Affect on Motion

Tue Sept 15. Dynamics - Newton s Laws of Motion. Forces: Identifying Forces Free-body diagram Affect on Motion Tue Sept 15 Assignment 4 Friday Pre-class Thursday Lab - Print, do pre-lab Closed toed shoes Exam Monday Oct 5 7:15-9:15 PM email me if class conflict or extended time Dynamics - Newton s Laws of Motion

More information

ΣF = 0 and Στ = 0 In 2-d: ΣF X = 0 and ΣF Y = 0 Goal: Write expression for Στ and ΣF

ΣF = 0 and Στ = 0 In 2-d: ΣF X = 0 and ΣF Y = 0 Goal: Write expression for Στ and ΣF Thur Sept 24 Assign 5 Friday Exam Mon Oct 5 Morton 235 7:15-9:15 PM Email if conflict Today: Rotation and Torques Static Equilibrium Sign convention for torques: (-) CW torque (+) CCW torque Equilibrium

More information

4) Vector = and vector = What is vector = +? A) B) C) D) E)

4) Vector = and vector = What is vector = +? A) B) C) D) E) 1) Suppose that an object is moving with constant nonzero acceleration. Which of the following is an accurate statement concerning its motion? A) In equal times its speed changes by equal amounts. B) In

More information

Phys101 Lecture 5 Dynamics: Newton s Laws of Motion

Phys101 Lecture 5 Dynamics: Newton s Laws of Motion Phys101 Lecture 5 Dynamics: Newton s Laws of Motion Key points: Newton s second law is a vector equation Action and reaction are acting on different objects Free-Body Diagrams Ref: 4-1,2,3,4,5,6,7. Page

More information

5. Forces and Free-Body Diagrams

5. Forces and Free-Body Diagrams 5. Forces and Free-Body Diagrams A) Overview We will begin by introducing the bulk of the new forces we will use in this course. We will start with the weight of an object, the gravitational force near

More information

Physics 207: Lecture 24. Announcements. No labs next week, May 2 5 Exam 3 review session: Wed, May 4 from 8:00 9:30 pm; here.

Physics 207: Lecture 24. Announcements. No labs next week, May 2 5 Exam 3 review session: Wed, May 4 from 8:00 9:30 pm; here. Physics 07: Lecture 4 Announcements No labs next week, May 5 Exam 3 review session: Wed, May 4 from 8:00 9:30 pm; here Today s Agenda ecap: otational dynamics and torque Work and energy with example Many

More information