Physics 218, Lecture IV1 Physics 218 Lecture 4 Dr. David Toback

Physics 218, Lecture IV2 Lecture from Bill Bassichis See Lecture 3 for problems and announcements for next week…

Physics 218, Lecture IV3

4 Announcements Notes on Lecture Assignments from the grader: 1.Make sure to write down your SECTION NUMBER on your assignment 2.Give a detailed explanation. Just writing down the right answer or a couple equations, isn’t enough 3.Make sure you answer the assigned problems 4.Don’t use ripped paper, or pulled from a notebook (frayed edges are insulting) 5.Improving your hand writing will help…

Physics 218, Lecture IV5 Today’s Lecture Finish up some math issues –Integrals Problem solving techniques –Motion in 1-Dimension continued –No longer going to use numbers –Examples: Stopping a speeding car Free fall Catching a speeder

Physics 218, Lecture IV6

7 Getting the Displacement from Velocity If you are given the velocity vs. time graph you can find the total distance traveled from the area under the curve: –X-X 0 =V 0 t + ½at 2 Can also find this from integrating… The Equation of Motion for Constant Acceleration: X=X 0 +V 0 t + ½at 2 Slope is constant = Constant acceleration

Physics 218, Lecture IV8 Definite and Indefinite Integrals

Physics 218, Lecture IV9 Some Integrals

Physics 218, Lecture IV10 Our Example with Const. Acceleration

Physics 218, Lecture IV11 How quickly can you stop a car? You’re driving along a road at some constant speed, V 0, and slam on the breaks and slow down with constant deceleration a. 1.How much time does it take to stop? 2.How far do you travel before you come to a stop? When you hit the brakes Where you stop

Physics 218, Lecture IV12 Free Fall Free fall is a good example for one dimensional problems Gravity Things accelerate towards earth with a constant acceleration I.e., a=g=9.8m/s 2 towards the earth –We’ll come back to Gravity a lot!

Physics 218, Lecture IV13 Throw a Ball up You throw a ball upward into the air with initial velocity V 0. Calculate: a)The time it takes to reach its highest point (the top). b)Distance from your hand to the top c)Time to go from your hand and come back to your hand d)Velocity when it reaches your hand e)Time from leaving your hand to reach some random height h.

Physics 218, Lecture IV14 Speeder A speeder passes you (a police officer) sitting by the side of the road and maintains their constant velocity V. You immediately start to move after the speeder from rest with constant acceleration a. How much time does it take to ram the speeder? How far do you have to travel to catch the speeder? What is your final speed? X Police Officer Speeder

Physics 218, Lecture IV15 Show that for constant acceleration:

Physics 218, Lecture IV16 Next Week Reading and Lecture: Chapter 3, Motion in two or three dimensions Reading Questions: Discussion Questions Q3.5 & Q3.6, due Tuesday at the beginning of class Recitation and WebCT Homework: –HW: HW1 due Monday in WebCT (noon) –Recitation: Chapter 2 –Recitation Prep: Do HW2 on paper, start turning in on WebCT before recitation –Lab: None

Physics 218, Lecture IV17

Physics 218, Lecture IV18 Announcements There is a link to a copy of all the handouts on my web page. There are even some handouts which I didn’t handout, but you should pick up. Please make sure you are checking your neo account and that you are receiving there. Please make sure that you are registered for 218 and not 208 on your Math quizzes!!

Physics 218, Lecture IV19 Next Week Reading: Chapter 3 Homework: –Turn in HW1 on the web by Monday at Noon I recommend you try at least once before the weekend –Be working on HW2. Web quiz: Finish `em. Labs and Recitations: As usual… Next week: Lectures on Chapter 3: Kinematics in two dimensions and vectors