About myself Office hours: by appointment Dr. Soeren Prell –Office: A417 Zaffarano –Phone: – Courses taught at ISU (since 2002) –Introduction to Classical Physics I + II –Modern Physics Lab –Quantum Mechanics I + II Research –Experimental elementary particle physics at the Large Hadron Collider (LHC) Hobby –Judo coach at Cyclone Martial Arts Club

The Physics 222 Instructor Team Lecturers: –Soeren Prell Course secretary –Deb Schmidt Lab supervisor –Paula Herrera Recitation and Lab Teaching Assistants: –Meijian Li, Carlos Vergel Infante, Kamal Raj Joshi, Andres Garcia, Kevin Marasinghe Chirag Vaswani, Bob Mayer, Ragavi Pala Janardhan, Krishna Leela Rajana

The syllabus Linked from Phys 222 course web page (under Course Info) – Lecturer contact information Textbook and other course material –Incl. for online homework Course schedule –Lectures, recitations, hw assignment due dates (online hw and reading), quizzes, exams, etc. Grading policy First homework assignment: read the syllabus carefully!

Exams 2 mid-semester exams –Evening exams at Final exam Wednesday, February 188:15 pm – 10:15 pm Wednesday, April 18:15 pm – 10:15 pm May 4 – 8time and day TBA, 120 minutes Make no other plans for these evenings !

Recitations Each Tuesday (50 minutes) –Worksheets (40 minutes) Hands-on, interactive learning –Quizzes (10 minutes)

Labs 14 two-hour labs Each section meets every week Prelab must be completed before corresponding lab Check lab schedule for dates and time of your session Detailed lab info on Blackboard –For questions regarding labs, Paula Herrera Questions based on material covered in recitations and labs will be on the exams !

Student Assistance Physics 222 help room (=TA office hours) Lecturer office hours Physics 222 course web page and info on Blackboard Discussion board on Blackboard SI session for Physics 222

How to succeed in Physics 222 Physics can only be learned by doing it (just like swimming or juggling) Lectures –Prepare for lecture Read the indicated assignments before class –Attend actively Ask questions, participate in interactive problems Homework –Do all problems –Review the HW solutions –Understand and learn from your mistakes

Lectures Turn off your cell phone in lecture No laptops in lecture Bring your clicker –Register it on the Physics 222 Blackboard page No need to bring your textbook Note taking –Lecture notes will be posted on the course web page before each lecture

Lecture 1 Fluids: density, pressure, Pascal’s principle. Water tower Hydraulic press Pascal’s vases Barometer

What is a fluid? Fluids are “substances that flow”…. “substances that take the shape of the container” Atoms and molecules must be free to move. No long range correlation between positions (e.g., not a crystal). Gas or liquid… or granular materials (like sand)

Density, pressure Density: Pressure: Units: Pascal (Pa) = 1 N/m 2 psi (pounds per square inch) atmosphere 1 atm = × 10 5 Pa bar1 bar = 10 5 Pa Units: Pascal (Pa) = 1 N/m 2 psi (pounds per square inch) atmosphere 1 atm = × 10 5 Pa bar1 bar = 10 5 Pa Pure water: 1000 kg/m 3

Atmospheric pressure DEMO: Piston and weight The atmosphere of Earth is a fluid, so every object in air is subject to some pressure. At the surface of the Earth, the pressure is p atm ~ x 10 5 Pa = 1 atm At the surface of the Earth, the pressure is p atm ~ x 10 5 Pa = 1 atm Area of a hand ~ 200 cm 2 = 0.02 m 2

Pressure vs. depth F bottom F top mg Imaginary box of fluid with density ρ with bases of area A and height h h Net force must be zero! DEMO: Plastic tube with cover

Fluid in an open container Pressure is the same at a given depth, independently of the container. Fluid level is the same everywhere in a connected container (assuming no surface forces) A B If liquid height was higher above A than above B p A > p B Net force Net flow This is not equilibrium! DEMO: Pascal’s vases

Water towers Water towers are a common sight in the Midwest… because it’s so flat! h h

So physics sucks, but how much? Your physics professor sucks on a long tube that rises out of a bucket of water. He can get the liquid to rise 5.5 m (vertically). What is the pressure in his mouth at this moment? A.1 atm B.0.67 atm C.0.57 atm D.0.46 atm E.0 atm A.1 atm B.0.67 atm C.0.57 atm D.0.46 atm E.0 atm DEMO: Sucking through a hose h h x A x B

Pascal’s principle Any change in the pressure applied to an enclosed fluid is transmitted to every portion of the fluid and to the walls of the containing vessel. Pascal’s Principle is most often applied to incompressible fluids (liquids): Increasing p at any depth (including the surface) gives the same increase in p at any other depth Pascal’s Principle is most often applied to incompressible fluids (liquids): Increasing p at any depth (including the surface) gives the same increase in p at any other depth

Hydraulic chamber F 2 can be very large… No energy is lost:

Measuring pressure with fluids Barometer è Measures absolute pressure è Top of tube evacuated (p = 0) è Bottom of tube submerged into pool of mercury open to sample (p) è Pressure dependence on depth: Barometer Sample at p h h Vacuum p 0 = 0 p p p atm ∆h∆h ∆h∆h p ΔhΔh p0p0 Manometer è Measures gauge pressure: pressure relative to a normalization pressure. è Pressure dependence on depth: A unit for pressure 760 mm Hg = 760 torr = 1/760 atm