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Do Now • Turn in Lab Report Today’s Agenda • Work Time for Test • CN: Newton’s 1st corrections and Unit and 2nd Laws 2 Startup Homework • Take notes on 5-1 to 5-3 o pg 108-118 • HW 1: #1-5 Projectile Results Average: 75.4% Old Average: 82.2% Do Now • Check yourself #1-5 Today’s Agenda • HW Questions • Film Clips Homework to be stamped tomorrow • Take notes on 5-1 to 5-3 (pg 108-118) • HW 1: # 8, HW 2: #1, 2, 4 Due Friday • Notes on all of chapter 5 Answers 1. 2. 3. 4. 5. 6. C A 4 A C Whiplash occurs because of inertia. Your head wants to stay in the same place. Your car moves your body forward but leaves your head behind. OUCH! Homework questions? How to Read a Chapter in a Physics Textbook …because you need to learn how to learn from reading And because there are no retakes Focus on one section at a time • Outline each section (5-1, 5-2, 5-3) in detail, paying attention to terms in bold and their definitions • Whenever possible try to write definitions in words and pictures • Avoid detailed mathematical equations. Most of the A.P. Physics exam uses very general equations – your understanding of the concepts is most crucial at this point. Don’t do too much at once! • Do not carry try to read the whole chapter in one sitting. It will take time to absorb all of the ideas. • Each chapter has a Summary at the end (don’t they always?) Do your notes cover all the concepts addressed in the summary? Use the example problems to check your understanding • The answers are end of the example, but you should carefully think through your answer before looking. Brain Break As you watch the clips, consider the following questions: • Where are Newton’s laws of force present? • Are Newton’s laws accurately portrayed? • Are any laws of physics broken in order to make the clip more interesting? If so, how? • What questions does this clip leave you with? Do Now • Take out Notes on 5-1 to 5-3 to be stamped • Check yourself #1-3 Today’s Agenda • Review Quiz • HW Questions • CN: Free body diagrams & 2nd law Homework • • • • FBD exercises (in HW packet) HW 1: #6, 7 & HW 2: # 3, 5, 6 Notes on all of chapter 5 Quiz Corrections (2 quizzes) Answers 1. B 2. B 3. D Corrections to the answer key • HW 2: #2a o 1125 N • HW 2: #4 o Answer is correct-ish, I made the answer negative because you are pushing DOWN. o HW 2: #7C o 55.2 m/s 2 Do Now • Turn in Quiz Corrections (there are 2!) • Turn in notes for Ch 5 • Check yourself #4-6 Today’s Agenda • HW Questions • Force Quiz 1 • Finish CN examples? Homework • HW 3: #1 & 4 HW 4: #5 & 6 • Start Notes for chapter 6 (they are due next Friday) Answers 1. 2. 3. 4. 5. 6. B B D C C B Do Now • Turn in notes for Ch 5 • Check yourself #1-4 Today’s Agenda • HW Questions • Finish CN examples? Homework • HW 3: #5 & 6 HW 4: #3 & 5 • Notes: 6-2 to 6-4 are due Friday Answers 1. 2. 3. 4. C B D E Newton’s Laws Results Average: 85.8 % Old Average: 75.4% Today’s Aim 1. Draw FBD for objects on slopes 2. Break Forces into x and y components 3. Compose Net Force equations HW 3: #5 A 34.5 kg block rests on the ramp as shown in the drawing. What is the tension in the line that is connected to the top of ramp? 35 Language Objective Students will be able to explain what force causes a ball to accelerate down a hill Do Now • Check yourself 9-10 Today’s Agenda • HW Questions • Finish CN examples? Homework • HW 3: #8, 9 HW 4: #4 HW 7: #1,2, 3 • Notes: 6-2 to 6-4 are due Friday Answers 9. B 10. D CHANGE in Schedule Week 2 (Objectives: 2c-1, 2c-2, 3a, 3b, 3c, 3d) Pulleys, Ramps, Net force & Newton's third law Write equation for Fnet = sum of all F acting in the x or y direction w/appropriate signs accounting for angles (+/-) Be able to draw the location and direction of friction on a FBD State Newton’s 3rd Law Be able to identify the action force, reaction force, and effects of both for given situations Week 3 (Objectives: 2d-1, 2d-2, 2d-3, 2e-1) Friction and terminal velocity Define friction Explain the variables that affect the strength of frictional force Know when to use the kinetic vs. static coefficient of friction Explain freefall and terminal velocity using Newton’s 2nd Law HW 3: #8 A 4.50 kg block rests on a smooth ramp as shown. It is attached to a 4.20 kg block by a very low mass string that is run over a low friction pulley. When the system is released, what direction will the blocks travel and what will their acceleration be? HW 3: #9 Two masses are connected by a light string that runs over a frictionless pulley as shown. What is the acceleration of the system when the masses are released and allowed to move? 2 .2 5 k g m1 2 .1 0 k g m2 HW 4: #4 Three masses are connected by a light string that passes over a frictionless pulley as shown. (a) What is the acceleration of the system? (b) What are the tensions in the strings? 4 .0 5 k g 2 .4 0 k g 6 .5 0 k g Do Now • Force Body Diagram Quiz Today’s Agenda • HW Questions • Newton’s Third Law Homework • HW 4: #1, 2; HW 3: 2, 3; HW 6: 1, 4, 7 • Quiz corrections due Friday • Notes: 6-2 to 6-4 are due Friday Friday HW: HW 5: #2; HW 6: #3, 6; HW 7 #11-15 Do Now • Turn in Quiz Corrections & Notes 6-2 to 6-4 • 3rd law check yourself! Today’s Agenda • HW Questions • Key points review • Shortest quiz ever • Film: Table Cloth Trick Homework • HW 5: #2; HW 6: #3, 6; HW 7 #11-15 • Binderize! (organize your papers) • Upcoming: Notes: 6-1 are due Tuesday Answers A.) 0.066 m/s2 B.) 0.033 m/s C.) 909.3 s = 15.1 min Let’s say you are 50 kg and throw a 1.1 kg space rock forwards, accelerating it at 3.0 m/s2. Assume the time for the throw is 0.5 s The block on the ramp moves up the slope. (Assume there is friction between the block and the slope). Fx = 5.00 kg Fx is more / equal / less than 0 5.00 kg 38.0 because: Fy = Fy is more / equal / less than 0 because: The block on the ramp moves up the slope. (Assume there is friction between the block and the slope). 5.00 kg 5.00 kg 38.0 An equivalent FBD would be: • Turn in HW 1-4 Do Now Today’s Agenda • HW Questions kinetic Friction Homework • CN: static and • • • • HW 5: 1, 2, 3; HW 6: #2, 3 Binderize! (organize your papers) Notes: 6-1 are due Tuesday Newton’s Law test on Friday Discuss • If gravity pulls downward on a textbook with a force of approximately 100N, how large of an upward force must you exert on the book to... • a) hold the book up, at rest? • b) move the book upward at a constant speed of 4m/s? Newton’s Laws Results Average: 53.3 % Old Average: 85.8% By the way… Question 3 was from Pg 125 of the textbook Corrections to the answer key o HW 1: #7C o 55.2 m/s 2 • HW 2: #2a o 1125 N o HW 4: #2 o 0.985 kg (thanks Chris) o HW 4: #5 o B) 2.36 s o C) 42.7 m o D) 6.38 m o HW 7: #3 o B) 2938 N Projectile Retakes • Monday & Tuesday lunch or after school Can replace scores for: – Projo Quizo 1 (out of 97 points) – The wretched projectile test (out of 100 points) • Turn in HW 1-4 Do Now Today’s Agenda • HW Questions kinetic Friction Homework • CN: static and • • • • HW 5: 1, 2, 3; HW 6: #2, 3 Binderize! (organize your papers) Notes: 6-1 are due Tuesday Newton’s Law test on Friday Do Now • Turn in Notes 6-1 • Turn in Quiz: Newton’s Laws (I need to grade it… >.< ) • Multiple Choice Practice #1-6 Today’s Agenda • HW Questions? velocity • Practice MC Q’s Homework • CN: terminal • HW 5: #4; HW 6: #5. 6; HW 7: #4, 5, 6 • Binderize Quiz tomorrow! • Newton’s Law test on Friday Answers 1. 2. 3. 4. 5. 6. A E E D C B Do Now • Binder Quiz! • Up next: Check yourself Terminal Velocity #5-8 and Friction review (both sides) Today’s Agenda • Friction Review • HW Questions? • Review Time. Homework • • • • HW 7: #7-10 Finish Review Questions Complete Test Corrections Study for Newton’s Law test on Friday Terminal Velocity Answers 5. D 6. A 7. A 8. D A Martian lander is approaching the surface. It is slowing its descent by firing its rocket motor. Which is the correct free-body diagram for the lander? A Martian lander is approaching the surface. It is slowing its descent by firing its rocket motor. Which is the correct free-body diagram for the lander? An elevator that has descended from the 50th floor is coming to a halt at the 1st floor. As it does, your apparent weight is A. B. C. D. More than your true weight. Less than your true weight. Equal to your true weight. Zero. An elevator that has descended from the 50th floor is coming to a halt at the 1st floor. As it does, your apparent weight is A. B. C. D. More than your true weight. Less than your true weight. Equal to your true weight. Zero. The terminal speed of a Styrofoam ball is 15 m/s. Suppose a Styrofoam ball is shot straight down with an initial speed of 30 m/s. Which velocity graph is correct? The terminal speed of a Styrofoam ball is 15 m/s. Suppose a Styrofoam ball is shot straight down with an initial speed of 30 m/s. Which velocity graph is correct? Rank order, from largest to smallest, the size of the friction forces to in these 5 different situations. The box and the floor are made of the same materials in all situations. A. B. C. D. E. fc > fb > fa > fa = fb > fd > fc > fc = fb > fc = fe > fd > fd = fc = fd = fb > fa. fe > fa. fe > fb. fd = fe. fe > fa. Rank order, from largest to smallest, the size of the friction forces to in these 5 different situations. The box and the floor are made of the same materials in all situations. A. B. C. D. E. fc > fb > fa > fa = fb > fd > fc > fc = fb > fc = fe > fb > fa. fd > fe > fa. fd = fe > fb. fc = fd = fe. fd = fe > fa. The coefficient of static friction is A. B. C. D. smaller than the coefficient of kinetic friction. equal to the coefficient of kinetic friction. larger than the coefficient of kinetic friction. not discussed in this chapter. The coefficient of static friction is A. B. C. D. smaller than the coefficient of kinetic friction. equal to the coefficient of kinetic friction. larger than the coefficient of kinetic friction. not discussed in this chapter. Correction to HW 5: #3 250.0 kg crate is being pulled across the floor at a constant velocity with a rope that makes an angle of 22.0 to the horizontal. If the force applied is equal to 875 N, what is the coefficient of kinetic friction?