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PHYSICS 101

PHYSICS 101. ENERGY Physics Chemistry -Life. Syllabus. Available online Highlights 3 Exams Sept. 27, Oct. 20, Nov 15 + Final Dec 13 =2 exams NO MAKE-UPS. Syllabus. TEXTBOOK College Physics Custom edition bookstore. Syllabus.

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PHYSICS 101

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  1. PHYSICS 101 ENERGY Physics Chemistry -Life

  2. Syllabus • Available online • Highlights 3 Exams Sept. 27, Oct. 20, Nov 15 + Final Dec 13 =2 exams NO MAKE-UPS

  3. Syllabus • TEXTBOOK • College Physics • Custom edition bookstore

  4. Syllabus • Studios (labs) • Begin week of Sept. 13. 10 Lab- Studios + 1 make-up • HW every week. Graded in studio

  5. Grades • 4 best exams 400 pts • Studio 135 pts • HW 65 pts

  6. There is more to lectures than the power point slides! • Engage your mind

  7. The scope of physics

  8. CO.03 • YouTube - Lion vs wildebeest - BBC wildlife

  9. Mars Rover

  10. Animation: Mars Science Laboratory - JPL, NASA: Multimedia, videos, animations, High definition, clips, free downloads#fragment-5

  11. Rover

  12. SCIENTIFIC NOTATION

  13. How Far is a Star? • The nearest star, α Centauri, is 44 Quadrillion meters or 44,000,000,000,000,000 meters away • What does this mean? • How can we keep track of all those zeros? • 0 is important!!

  14. Example The radius of the sun is 700,000 km. Write as 7.0105 km. When properly written this number will be between 1.0 and 10.0 Example: The radius of a hydrogen atom is 0.0000000000529 m. This is more easily written as 5.2910-11 m.

  15. Arithmetic with Scientific Notation • Multiplication -> Add Exponents e.g. 107 x 103 = 107+3 = 1010 • Division -> Subtract exponents e.g. 107/103 = 107-3 =104 • Negative powers are inverses e.g. 10-3 = 1/103 • 10 x 10-1 =10/10 =1 = 101-1= 100

  16. Significant Figures • Nonzero digits are always significant. • Final ending zeroes written to the right of the decimal aresignificant. (Example: 7.00.) • Zeroes that are placeholders are not significant. (Example: 700,000 versus 700,000.0.) • Zeroes written between digits are significant. (Example: 105,000; 150,000.)

  17. Significant Figures: Division • Find the value of 6.49m divided by 5.1037s • Calculator gives 1.271626467 ! • Too many figures. FALSE Accuracy • Only 3 significant figures. Why? • 1.27m/s

  18. ESTIMATION Estimate the number of times a human heart beats during its lifetime. • 2.4 x 109 beats/lifetime Estimate - a typical heart beats ~60 times per minute:

  19. Life in terms of heart beats • Almost all mammals from tiny shrews to huge elephants live about a billion heartbeats!

  20. Describing motion

  21. Motion-The Particle Model A simplifying model in which we treat the object as if all its mass were concentrated at a single point. This model helps us concentrate on the overall motion of the object. Slide 1-16

  22. Position and Time The position of an object is located along a coordinate system. At each time t, the object is at some particular position. We are free to choose the origin of time (i.e., when t = 0). Slide 1-17

  23. Displacement The change in the position of an object as it moves from initial position xi to final position xf is its displacement ∆x = xf – xi. Slide 1-18

  24. Checking Understanding • Maria is at position x = 23 m. She then undergoes a displacement ∆x = –50 m. What is her final position? • –27 m • –50 m • 23 m • 73 m Slide 1-19

  25. Answer • Maria is at position x = 23 m. She then undergoes a displacement ∆x = –50 m. What is her final position? • –27 m • –50 m • 23 m • 73 m Slide 1-20

  26. Speed of a Moving Object O O O O O O O O O O Slide 1-25

  27. Speed of a Moving Object 40 m m 1 s s 20 m m 1 s s The car moves 40 m in 1 s. Its speed is = 40 . The bike moves 20 m in 1 s. Its speed is = 20 . Slide 1-25

  28. Checking Understanding Two runners jog along a track. The positions are shown at 1 s time intervals. Which runner is moving faster? Slide 1-21

  29. Answer Two runners jog along a track. The positions are shown at 1 s time intervals. Which runner is moving faster? A Slide 1-22

  30. Velocity of a Moving Object Slide 1-26

  31. Vectors A quantity that requires both a magnitude (or size) and a direction can be represented by a vector. Graphically, we represent a vector by an arrow. The velocity of this car is 100 m/s (magnitude) to the left (direction). This boy pushes on his friend with a force of 25 N to the right. Slide 1-32

  32. Displacement is a vector Velocity is a vector

  33. Displacement Vectors A displacement vector starts at an object’s initial position and ends at its final position. It doesn’t matter what the object did in between these two positions. In motion diagrams, the displacement vectors span successive particle positions. Slide 1-33

  34. Vectors versus scalars: A scalar is just a number (no direction). The mass of an object is an example of a scalar quantity.Volume is a scalar A vector is a quantity that has both a magnitude and a direction. Velocity is an example of a vector quantity. Force is a vector

  35. Vectors To graphically represent a vector, draw a directed line segment. The length of the line can be used to represent the vector’s length or magnitude.

  36. Notation: Scalar: m (not bold face; no arrow) Vector: The magnitude of a vector: The direction of vector might be “35 south of east”; “20 above the +x-axis”; or….

  37. Adding vectors To add vectors graphically they must be placed “tip to tail”. The result (F1 + F2) points from the tail of the first vector to the tip of the second vector. F1 F2 For collinear vectors: Fnet ? F1 F2 Fnet ?

  38. Adding Vectors Lengthb Lengtha c Θb a a2+ b2= c2 Tan θ =b/a

  39. Adding Vectors • Same result as before Can also add

  40. Components a=c cosθ b=c sinθ c b θ a2 +b2= c2 a

  41. How fast is this plane moving? 200 100 Cross wind

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