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PHYS16 – Lecture 3

PHYS16 – Lecture 3. Physics of 1D Motion Friday, September 10, 2010. Looney Tunes. Agenda. Administration Vectors Review from last week Key Concepts – Physics 1D motion Displacement, Velocity, & Acceleration. Administration. Register Clickers Textbook

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PHYS16 – Lecture 3

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  1. PHYS16 – Lecture 3 Physics of 1D Motion Friday, September 10, 2010 Looney Tunes

  2. Agenda • Administration • Vectors • Review from last week • Key Concepts – Physics 1D motion • Displacement, Velocity, & Acceleration

  3. Administration • Register Clickers • Textbook • University Physics vol. 1 by Bauer & Westfall • Connect Physics • http://connect.mcgraw-hill.com/class/a_carter_fall_2010 • Math Exam • Homework Assignments • On course website • On Connect website

  4. Review from last week • Significant figures • Every digit that has meaning (not trailing or leading zeros) • 0.00543 has 3 significant figures • When multiply/divide keep # of sig figs of number with lowest amount of sig figs • When add/subtract keep # to the lowest decimal • Scientific Notation • Way of expressing number with sig figs and order of magnitude • 12,300,000 is 1.23E7 • Units • Know prefixes – milli = 10^-3, kilo=10^3 • Conversion • If 1 M = 1 mol/L then 4.0 mol in 3.0 L is? 4.0 mol/3.0 L = 1.3 M • If 25.4 mm = 1 in then 3.2 in = mm? 3.2 in*25.4 mm/in= 81 mm

  5. Vectors • Vector vs. Scalar • Vector – quantity with both magnitude and direction • Scalar – quantity with just magnitude • Which is a vector and which is a scalar? • 25 apples in a bucket (scalar) • Car coming at me at 100 mph (vector) • I live 6 miles from grandma (scalar) • Grandma’s house is 6 miles east of here (vector)

  6. Vector • Representation • Finding Vector components – Use Trig!!!

  7. Math Review Questions 1 Let’s say we make a measurement of our position with 3 different GPS devices (GPS watch, GPS phone, and a car GPS) and we know that we are right next to the bank (red x). Which GPS is the most ACCURATE? • GPS watch • GPS phone • Car GPS BANK GROCERY

  8. Math Review Questions 2 Let’s say we make a measurement of our position with 3 different GPS devices (GPS watch, GPS phone, and a car GPS) and we know that we are right next to the bank (red x). Which GPS is the most PRECISE? • GPS watch • GPS phone • Car GPS BANK GROCERY

  9. Math Review Questions 3 A problem asks you to find the pressure (P) a piston exerts given a force (F) of 23.7 N and a length (l) and width (w) of the piston of 11 cm and 0.001 km, respectively. The equation that governs this is P=F/(lw). How many significant digits should you enter in your answer? A. 1 B. 2 C. 3 D. 4 E. There is not enough information.

  10. Math Review Questions 4 A problem asks you to find the pressure (P) a piston exerts given a force (F) of 23.7 lbs and a length (l) and width (w) of the piston of 11 in and 0.001 in, respectively. The equation that governs this is P=F/(lw). What are the units of pressure? A.lbs B. in C. lbs/in D. lbs/(in^2) E. There is not enough information.

  11. Math Review Questions 5 What is the value for V3? • (4,4) • (-2,2) • (2,-2) • (3,3) • (4,3) V3=? V2= (1,3) V1= (3,1)

  12. Key Concepts: Physics 1D Motion • Displacement, Velocity, & Acceleration • Know the definitions of these terms • Know how they are related • Motion with Constant Acceleration • Solve the equations of Motion for constant accel. • Know the 5 kinematic equations • Use the kinematic equations to solve problems

  13. Displacement • Displacement vs. Distance • Displacement = final position – initial position with both magnitude and direction • Distance = total position traversed from final position to initial position, just magnitude

  14. Velocity • Velocity vs. Speed • Velocity – final position minus initial position divided by time, both magnitude and direction • Speed – how fast you are going, just magnitude 60 mph

  15. Acceleration • Acceleration • Final velocity minus initial velocity divided by time, both a magnitude and a direction • How much an object speeds up or slows down Position graph where acceleration is not 0 http://physics247. com

  16. Questions • Can displacement be zero and distance be positive? (Yes) • Can distance ever be negative? (No) • Can speed ever be negative? (No) • Can acceleration be negative? (Yes) • Can an object that is stopped at t=0 have a positive acceleration? (Yes) • If an object is traveling at a constant velocity can it have an acceleration? (No)

  17. For Next Time… • Online homework due Tuesday • Online lab homework due Wednesday • Online Math Exam due Sunday • Get your clicker, text, connect access…

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