Your Comments. That s the plan

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

Review for 3 rd Midterm

Review for 3 rd Midterm Review for 3 rd Midterm Midterm is on 4/19 at 7:30pm in the same rooms as before You are allowed one double sided sheet of paper with any handwritten notes you like. The moment-of-inertia about the center-of-mass

More information

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

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

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

Chapter 9- Static Equilibrium

Chapter 9- Static Equilibrium Chapter 9- Static Equilibrium Changes in Office-hours The following changes will take place until the end of the semester Office-hours: - Monday, 12:00-13:00h - Wednesday, 14:00-15:00h - Friday, 13:00-14:00h

More information

PHY 1150 Doug Davis Chapter 8; Static Equilibrium 8.3, 10, 22, 29, 52, 55, 56, 74

PHY 1150 Doug Davis Chapter 8; Static Equilibrium 8.3, 10, 22, 29, 52, 55, 56, 74 PHY 1150 Doug Davis Chapter 8; Static Equilibrium 8.3, 10, 22, 29, 52, 55, 56, 74 8.3 A 2-kg ball is held in position by a horizontal string and a string that makes an angle of 30 with the vertical, as

More information

Physics 2210 Fall smartphysics Rotational Statics 11/18/2015

Physics 2210 Fall smartphysics Rotational Statics 11/18/2015 Physics 2210 Fall 2015 smartphysics 17-18 Rotational Statics 11/18/2015 τ TT = L T 1 sin 150 = 1 T 2 1L Poll 11-18-01 τ TT = L 2 T 2 sin 150 = 1 4 T 2L 150 150 τ gg = L 2 MM sin +90 = 1 2 MMM +90 MM τ

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

Lecture 22: Harmonic Waves. Physics 2210 Fall Semester 2014

Lecture 22: Harmonic Waves. Physics 2210 Fall Semester 2014 Lecture 22: Harmonic Waves Physics 2210 Fall Semester 2014 Announcements Unit 21 Simple and Physical Pendula (Nov 24th ) HW Due 11/25 th as usual No new material Wednesday November 26th. In-class discussion

More information

Announcements Oct 17, 2013

Announcements Oct 17, 2013 Announcements Oct 17, 2013 1. No announcements! Colton - Lecture 14 - pg 1 Real satellites: http://science.nasa.gov/realtime/jtrack/3d/jtrack3d.html International space station, 340.5 km above surface

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

CHAPTER 8 TEST REVIEW MARKSCHEME

CHAPTER 8 TEST REVIEW MARKSCHEME AP PHYSICS Name: Period: Date: 50 Multiple Choice 45 Single Response 5 Multi-Response Free Response 3 Short Free Response 2 Long Free Response MULTIPLE CHOICE DEVIL PHYSICS BADDEST CLASS ON CAMPUS AP EXAM

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

Welcome back to Physics 211

Welcome back to Physics 211 Welcome back to Physics 211 Today s agenda: Weight Friction Tension 07-1 1 Current assignments Thursday prelecture assignment. HW#7 due this Friday at 5 pm. 07-1 2 Summary To solve problems in mechanics,

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 2101, Final Exam, Spring 2007

Physics 2101, Final Exam, Spring 2007 Physics 2101, Final Exam, Spring 2007 May 10, 2007 Name : Section: (Circle one) 1 (Rupnik, MWF 7:40am) 2 (Giammanco, MWF 9:40am) 3 (Rupnik, MWF 11:40am) 4 (Rupnik, MWF 2:40pm) 5 (Giammanco, TTh 10:40am)

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

Physics 8 Monday, October 12, 2015

Physics 8 Monday, October 12, 2015 Physics 8 Monday, October 12, 2015 HW5 will be due Friday. (HW5 is just Ch9 and Ch10 problems.) You re reading Chapter 12 ( torque ) this week, even though in class we re just finishing Ch10 / starting

More information

1 MR SAMPLE EXAM 3 FALL 2013

1 MR SAMPLE EXAM 3 FALL 2013 SAMPLE EXAM 3 FALL 013 1. A merry-go-round rotates from rest with an angular acceleration of 1.56 rad/s. How long does it take to rotate through the first rev? A) s B) 4 s C) 6 s D) 8 s E) 10 s. A wheel,

More information

Unit 1: Equilibrium and Center of Mass

Unit 1: Equilibrium and Center of Mass Unit 1: Equilibrium and Center of Mass FORCES What is a force? Forces are a result of the interaction between two objects. They push things, pull things, keep things together, pull things apart. It s really

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 8 Friday, October 20, 2017

Physics 8 Friday, October 20, 2017 Physics 8 Friday, October 20, 2017 HW06 is due Monday (instead of today), since we still have some rotation ideas to cover in class. Pick up the HW07 handout (due next Friday). It is mainly rotation, plus

More information

HATZIC SECONDARY SCHOOL

HATZIC SECONDARY SCHOOL HATZIC SECONDARY SCHOOL PROVINCIAL EXAMINATION ASSIGNMENT STATIC EQUILIBRIUM MULTIPLE CHOICE / 33 OPEN ENDED / 80 TOTAL / 113 NAME: 1. State the condition for translational equilibrium. A. ΣF = 0 B. ΣF

More information

Physics 8 Wednesday, October 25, 2017

Physics 8 Wednesday, October 25, 2017 Physics 8 Wednesday, October 25, 2017 HW07 due Friday. It is mainly rotation, plus a couple of basic torque questions. And there are only 8 problems this week. For today, you read (in Perusall) Onouye/Kane

More information

Unit 06 Examples. Stuff you asked about:

Unit 06 Examples. Stuff you asked about: Unit 06 Examples Today s Concepts: 1. Force due to gravity 2. Force due to strings 3. Force due to springs (just a little bit) Mechanics Lecture 5, Slide 1 Stuff you asked about: Can you go over all of

More information

Lecture 5. Dynamics. Forces: Newton s First and Second

Lecture 5. Dynamics. Forces: Newton s First and Second Lecture 5 Dynamics. Forces: Newton s First and Second What is a force? It s a pull or a push: F F Force is a quantitative description of the interaction between two physical bodies that causes them to

More information

Chapter 4 Force and Motion

Chapter 4 Force and Motion Chapter 4 Force and Motion Units of Chapter 4 The Concepts of Force and Net Force Inertia and Newton s First Law of Motion Newton s Second Law of Motion Newton s Third Law of Motion More on Newton s Laws:

More information

PY205N Spring The vectors a, b, and c. are related by c = a b. The diagram below that best illustrates this relationship is (a) I

PY205N Spring The vectors a, b, and c. are related by c = a b. The diagram below that best illustrates this relationship is (a) I PY205N Spring 2013 Final exam, practice version MODIFIED This practice exam is to help students prepare for the final exam to be given at the end of the semester. Please note that while problems on 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

Physics 125, Spring 2006 Monday, May 15, 8:00-10:30am, Old Chem 116. R01 Mon. 12:50 R02 Wed. 12:50 R03 Mon. 3:50. Final Exam

Physics 125, Spring 2006 Monday, May 15, 8:00-10:30am, Old Chem 116. R01 Mon. 12:50 R02 Wed. 12:50 R03 Mon. 3:50. Final Exam Monday, May 15, 8:00-10:30am, Old Chem 116 Name: Recitation section (circle one) R01 Mon. 12:50 R02 Wed. 12:50 R03 Mon. 3:50 Closed book. No notes allowed. Any calculators are permitted. There are no trick

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

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

Physics 8 Friday, November 4, 2011

Physics 8 Friday, November 4, 2011 Physics 8 Friday, November 4, 2011 Please turn in Homework 7. I will hand out solutions once everyone is here. The handout also includes HW8 and a page or two of updates to the equation sheet needed to

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. Common Quiz Mistakes / Practice for Final Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A ball is thrown directly upward and experiences

More information

Chapter 10: Dynamics of Rotational Motion

Chapter 10: Dynamics of Rotational Motion Chapter 10: Dynamics of Rotational Motion What causes an angular acceleration? The effectiveness of a force at causing a rotation is called torque. QuickCheck 12.5 The four forces shown have the same strength.

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

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

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

is the study of and. We study objects. is the study of and. We study objects.

is the study of and. We study objects. is the study of and. We study objects. Static Equilibrium Translational Forces Torque Unit 4 Statics Dynamics vs Statics is the study of and. We study objects. is the study of and. We study objects. Recall Newton s First Law All objects remain

More information

Exam 1 Stats: Average: 60% Approximate letter grade? Add 10%-12% (This is not a curve) This takes into account the HW, Lab, and Grade Replacement.

Exam 1 Stats: Average: 60% Approximate letter grade? Add 10%-12% (This is not a curve) This takes into account the HW, Lab, and Grade Replacement. Lec 11 Return Exam1 Intro Forces Tuesday, February 19, 2019 1:52 PM Exam 1 Stats: Average: 60% Approximate letter grade? Add 10%-12% (This is not a curve) This takes into account the HW, Lab, and Grade

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

General Physics I Forces

General Physics I Forces General Physics I Forces Dynamics Isaac Newton (1643-1727) published Principia Mathematica in 1687. In this work, he proposed three laws of motion based on the concept of FORCE. A force is a push or a

More information

Physics 1A Lecture 10B

Physics 1A Lecture 10B Physics 1A Lecture 10B "Sometimes the world puts a spin on life. When our equilibrium returns to us, we understand more because we've seen the whole picture. --Davis Barton Cross Products Another way to

More information

Homework #19 (due Friday 5/6)

Homework #19 (due Friday 5/6) Homework #19 (due Friday 5/6) Physics ID number Group Letter One issue that people often have trouble with at this point is distinguishing between tangential acceleration and centripetal acceleration for

More information

Problem Set x Classical Mechanics, Fall 2016 Massachusetts Institute of Technology. 1. Moment of Inertia: Disc and Washer

Problem Set x Classical Mechanics, Fall 2016 Massachusetts Institute of Technology. 1. Moment of Inertia: Disc and Washer 8.01x Classical Mechanics, Fall 2016 Massachusetts Institute of Technology Problem Set 10 1. Moment of Inertia: Disc and Washer (a) A thin uniform disc of mass M and radius R is mounted on an axis passing

More information

Lecture 2 - Force Analysis

Lecture 2 - Force Analysis Lecture 2 - orce Analysis A Puzzle... Triangle or quadrilateral? 4 distinct points in a plane can either be arrange as a triangle with a point inside or as a quadrilateral. Extra Brownie Points: Use the

More information

Q1. Which of the following is the correct combination of dimensions for energy?

Q1. Which of the following is the correct combination of dimensions for energy? Tuesday, June 15, 2010 Page: 1 Q1. Which of the following is the correct combination of dimensions for energy? A) ML 2 /T 2 B) LT 2 /M C) MLT D) M 2 L 3 T E) ML/T 2 Q2. Two cars are initially 150 kilometers

More information

Rotation. PHYS 101 Previous Exam Problems CHAPTER

Rotation. PHYS 101 Previous Exam Problems CHAPTER PHYS 101 Previous Exam Problems CHAPTER 10 Rotation Rotational kinematics Rotational inertia (moment of inertia) Kinetic energy Torque Newton s 2 nd law Work, power & energy conservation 1. Assume that

More information

LECTURE 22 EQUILIBRIUM. Instructor: Kazumi Tolich

LECTURE 22 EQUILIBRIUM. Instructor: Kazumi Tolich LECTURE 22 EQUILIBRIUM Instructor: Kazumi Tolich Lecture 22 2 Reading chapter 11-3 to 11-4 Static equilibrium Center of mass and balance Static equilibrium 3 If a rigid object is in equilibrium (constant

More information

Physics 8 Wednesday, October 11, 2017

Physics 8 Wednesday, October 11, 2017 Physics 8 Wednesday, October 11, 2017 HW5 due Friday. It s really Friday this week! Homework study/help sessions (optional): Bill will be in DRL 2C6 Wednesdays from 4 6pm (today). Grace will be in DRL

More information

EXAM 3 MECHANICS 40% of the final grade

EXAM 3 MECHANICS 40% of the final grade EXAM 3 MECHANICS 40% of the final grade Winter 2018 Name: Each multiple-choice question is worth 2 marks. 1. The mass of the two wheels shown in the diagram is the same. A force of 1 N is exerted on the

More information

PHYSICS 221 SPRING 2013

PHYSICS 221 SPRING 2013 PHYSICS 221 SPRING 2013 EXAM 2: April 4, 2013 8:15-10:15pm Name (printed): Recitation Instructor: Section # INSTRUCTIONS: This exam contains 25 multiple-choice questions plus 2 extra credit questions,

More information

Physics 101 Lecture 12 Equilibrium

Physics 101 Lecture 12 Equilibrium Physics 101 Lecture 12 Equilibrium Assist. Prof. Dr. Ali ÖVGÜN EMU Physics Department www.aovgun.com Static Equilibrium q Equilibrium and static equilibrium q Static equilibrium conditions n Net eternal

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

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

Physics 101. Hour Exam 2 Spring Last Name: First Name Network-ID Discussion Section: Discussion TA Name:

Physics 101. Hour Exam 2 Spring Last Name: First Name Network-ID Discussion Section: Discussion TA Name: Last Name: First Name Network-ID Discussion Section: Discussion TA Name: Instructions Turn off your cell phone and put it away. This is a closed book exam. You have ninety (90) minutes to complete it.

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

(1) +0.2 m/s (2) +0.4 m/s (3) +0.6 m/s (4) +1 m/s (5) +0.8 m/s

(1) +0.2 m/s (2) +0.4 m/s (3) +0.6 m/s (4) +1 m/s (5) +0.8 m/s 77777 77777 Instructor: Biswas/Ihas/Whiting PHYSICS DEPARTMENT PHY 2053 Exam 2, 120 minutes November 13, 2009 Name (print, last first): Signature: On my honor, I have neither given nor received unauthorized

More information

Classical Mechanics Lecture 9

Classical Mechanics Lecture 9 Classical Mechanics Lecture 9 Today's Concepts: a) Energy and Fric6on b) Poten6al energy & force Mechanics Lecture 9, Slide 1 Some comments about the course Spring examples with numbers Bring out a spring!

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

Sara Rwentambo. PHYS 1007 AB

Sara Rwentambo. PHYS 1007 AB Topics: Free body diagrams (FBDs) Static friction and kinetic friction Tension and acceleration of a system Tension in dynamic equilibrium (bonus question) Opener: Find Your Free Body Diagram Group Activity!

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

STUDY GUIDE 4: Equilibrium, Angular Kinematics, and Dynamics

STUDY GUIDE 4: Equilibrium, Angular Kinematics, and Dynamics PH 1110 Term C11 STUDY GUIDE 4: Equilibrium, Angular Kinematics, and Dynamics Objectives 25. Define torque. Solve problems involving objects in static equilibrium. 26. Define angular displacement, angular

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

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 221, FALL 2011 EXAM #2 SOLUTIONS WEDNESDAY, NOVEMBER 2, 2011

PHYSICS 221, FALL 2011 EXAM #2 SOLUTIONS WEDNESDAY, NOVEMBER 2, 2011 PHYSICS 1, FALL 011 EXAM SOLUTIONS WEDNESDAY, NOVEMBER, 011 Note: The unit vectors in the +x, +y, and +z directions of a right-handed Cartesian coordinate system are î, ĵ, and ˆk, respectively. In this

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

Physics 8 Monday, October 28, 2013

Physics 8 Monday, October 28, 2013 Physics 8 Monday, October 28, 2013 Turn in HW8 today. I ll make them less difficult in the future! Rotation is a hard topic. And these were hard problems. HW9 (due Friday) is 7 conceptual + 8 calculation

More information

Chapter 4. Forces and Newton s Laws of Motion. continued

Chapter 4. Forces and Newton s Laws of Motion. continued Chapter 4 Forces and Newton s Laws of Motion continued Quiz 3 4.7 The Gravitational Force Newton s Law of Universal Gravitation Every particle in the universe exerts an attractive force on every other

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

PHYSICS - CLUTCH CH 13: ROTATIONAL EQUILIBRIUM.

PHYSICS - CLUTCH CH 13: ROTATIONAL EQUILIBRIUM. !! www.clutchprep.com EXAMPLE: POSITION OF SECOND KID ON SEESAW EXAMPLE: A 4 m-long seesaw 50 kg in mass and of uniform mass distribution is pivoted on a fulcrum at its middle, as shown. Two kids sit on

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

Lecture 3 - Pull! A Puzzle... m g. m g. = d Sin[θ] F μ N 1 (2)

Lecture 3 - Pull! A Puzzle... m g. m g. = d Sin[θ] F μ N 1 (2) Lecture 3 - Pull! A Puzzle... Recall from last time that we computed the stability criterion 1 an[] for a leaning ladder (of length d): 2 μ We computed the stability using the base of the ladder as the

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

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

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

PHYSICS 220 Lecture 04 Forces and Motion in 1 D Textbook Sections

PHYSICS 220 Lecture 04 Forces and Motion in 1 D Textbook Sections PHYSICS 220 Lecture 04 Forces and Motion in 1 D Textbook Sections 3.2 3.6 Lecture 4 Purdue University, Physics 220 1 Last Lecture Constant Acceleration x = x 0 + v 0 t + ½ at 2 v = v 0 + at Overview v

More information

Old Exam. Question Chapter 7 072

Old Exam. Question Chapter 7 072 Old Exam. Question Chapter 7 072 Q1.Fig 1 shows a simple pendulum, consisting of a ball of mass M = 0.50 kg, attached to one end of a massless string of length L = 1.5 m. The other end is fixed. If the

More information

Force 10/01/2010. (Weight) MIDTERM on 10/06/10 7:15 to 9:15 pm Bentley 236. (Tension)

Force 10/01/2010. (Weight) MIDTERM on 10/06/10 7:15 to 9:15 pm Bentley 236. (Tension) Force 10/01/2010 = = Friction Force (Weight) (Tension), coefficient of static and kinetic friction MIDTERM on 10/06/10 7:15 to 9:15 pm Bentley 236 2008 midterm posted for practice. Help sessions Mo, Tu

More information

Answers to selected problems from Essential Physics, Chapter 10

Answers to selected problems from Essential Physics, Chapter 10 Answers to selected problems from Essential Physics, Chapter 10 1. (a) The red ones have the same speed as one another. The blue ones also have the same speed as one another, with a value twice the speed

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

PHYSICS 111 SPRING EXAM 2: March 7, 2017; 8:15-9:45 pm

PHYSICS 111 SPRING EXAM 2: March 7, 2017; 8:15-9:45 pm PHYSICS 111 SPRING 017 EXAM : March 7, 017; 8:15-9:45 pm Name (printed): Recitation Instructor: Section # INSTRUCTIONS: This exam contains 0 multiple-choice questions plus 1 extra credit question, each

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

Chapter 9. Rotational Dynamics

Chapter 9. Rotational Dynamics Chapter 9 Rotational Dynamics In pure translational motion, all points on an object travel on parallel paths. The most general motion is a combination of translation and rotation. 1) Torque Produces angular

More information

Equilibrium. Lecture 8 Physics 106 Spring Equilibrium. Equilibrium. Equilibrium. Balance of Forces: Balance of Forces: Balance of Torques:

Equilibrium. Lecture 8 Physics 106 Spring Equilibrium. Equilibrium. Equilibrium. Balance of Forces: Balance of Forces: Balance of Torques: Lecture 8 Physics 106 Spring 2006 http://web.njit.edu/~sirenko/ 3/8/2006 Andrei Sirenko, JIT 1 3/8/2006 Andrei Sirenko, JIT 2 3/8/2006 Andrei Sirenko, JIT 3 3/8/2006 Andrei Sirenko, JIT 4 3/8/2006 Andrei

More information

Unit 4 Statics. Static Equilibrium Translational Forces Torque

Unit 4 Statics. Static Equilibrium Translational Forces Torque Unit 4 Statics Static Equilibrium Translational Forces Torque 1 Dynamics vs Statics Dynamics: is the study of forces and motion. We study why objects move. Statics: is the study of forces and NO motion.

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

Lecture Presentation Chapter 8 Equilibrium and Elasticity

Lecture Presentation Chapter 8 Equilibrium and Elasticity Lecture Presentation Chapter 8 Equilibrium and Elasticity Suggested Videos for Chapter 8 Prelecture Videos Static Equilibrium Elasticity Video Tutor Solutions Equilibrium and Elasticity Class Videos Center

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

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

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

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

Gravitational potential energy

Gravitational potential energy Gravitational potential energ m1 Consider a rigid bod of arbitrar shape. We want to obtain a value for its gravitational potential energ. O r1 1 x The gravitational potential energ of an assembl of N point-like

More information

Physics 201 Midterm Exam 3

Physics 201 Midterm Exam 3 Name: Date: _ Physics 201 Midterm Exam 3 Information and Instructions Student ID Number: Section Number: TA Name: Please fill in all the information above Please write and bubble your Name and Student

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

It will be most difficult for the ant to adhere to the wheel as it revolves past which of the four points? A) I B) II C) III D) IV

It will be most difficult for the ant to adhere to the wheel as it revolves past which of the four points? A) I B) II C) III D) IV AP Physics 1 Lesson 16 Homework Newton s First and Second Law of Rotational Motion Outcomes Define rotational inertia, torque, and center of gravity. State and explain Newton s first Law of Motion as it

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

= 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