About myself • Dr. Soeren Prell • Office: A417 Zaffarano • Phone: 294-3853 • E-mail: email@example.com • 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 Office hours: by appointment
The Physics 222 Instructor Team • Lecturers: • Soeren Prell • Course secretary • Deb Schmidt • Lab supervisor • Paula Herrera • Recitation TeachingAssistants: • TBA • Lab Teaching Assistants: • TBA
The syllabus • Linked from Phys 222 course web page (under Course Info) • http://course.physastro.iastate.edu/phys222/ • 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, February19 8:15 pm – 10:15 pm Wednesday, April 2 8:15 pm – 10:15 pm Make no other plans for these evenings ! May 5 – 9time and day TBA, 120 minutes
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, e-mail Paula Herrera (firstname.lastname@example.org). 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 bike riding) • 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: Pure water: 1000 kg/m3 Pressure: Units: Pascal (Pa) = 1 N/m2 psi (pounds per square inch) atmosphere 1 atm = 1.013 × 105 Pa bar 1 bar = 105 Pa
DEMO: Piston and weight Atmospheric pressure • 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 • patm ~ 1.013 x 105 Pa = 1 atm • Area of a hand ~ 200 cm2 = 0.02 m2
Ftop mg Fbottom Net force must be zero! Pressure vs. depth DEMO: Plastic tube with cover Imaginary box of fluid with density ρwith bases of area A and height h h
DEMO: Pascal’s vases • 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 Net force Net flow This is not equilibrium! pA > pB Fluid in an open container Pressure is the same at a given depth, independently of the container.
Water towers Water towers are a common sight in the Midwest… because it’s so flat! h
DEMO: Sucking through a hose 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? x B h • 1 atm • 0.67 atm • 0.57 atm • 0.46 atm • 0 atm x A
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
Hydraulic chamber F2 can be very large… No energy is lost:
Vacuum p = 0 Barometer h Sample at p Manometer p0 p • Measures gauge pressure:pressure relative to atmospheric pressure. • Pressure dependence on depth: patm p Δh ∆h Measuring pressure with fluids Barometer • Measures absolute pressure • Top of tube evacuated (p = 0) • Bottom of tube submerged into pool of mercury open to sample (p) • Pressure dependence on depth: A unit for pressure 760 mm Hg = 1 torr = 1 atm