Physics 201. Professor P. Q. Hung. 311B, Physics Building. Physics 201 p. 1/2

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1 Physics 201 p. 1/2 Physics 201 Professor P. Q. Hung 311B, Physics Building

2 Physics 201 p. 2/2 Some Information Class website: xz5y/phys201/

3 Physics 201 p. 2/2 Some Information Class website: xz5y/phys201/ All course information is on the above Website

4 Physics 201 p. 2/2 Some Information Class website: xz5y/phys201/ All course information is on the above Website Go to UVaCollab under Resources after every lecture to look at the notes.

5 Physics 201 p. 2/2 Some Information Class website: xz5y/phys201/ All course information is on the above Website Go to UVaCollab under Resources after every lecture to look at the notes. Let s go through some things

6 Physics 201 p. 3/2 What you need for the course Textbook: Physics, 4th Edition by Walker, and Mastering Physics

7 Physics 201 p. 3/2 What you need for the course Textbook: Physics, 4th Edition by Walker, and Mastering Physics iclicker: Important to understand the policy (class website) for using this unit.

8 Physics 201 p. 4/2 Course Objectives: To learn and understand the physical world

9 Physics 201 p. 4/2 Course Objectives: To learn and understand the physical world How? Problem Solving and Conceptual Understanding.

10 Physics 201 p. 4/2 Course Objectives: To learn and understand the physical world How? Problem Solving and Conceptual Understanding. How to achieve that? Lectures Reading and Conceptual quizzes in class Homeworks Discussion Section Quizzes

11 Physics 201 p. 5/2 Homework assignments Homeworks will be found and submitted on MasteringPhysics. Register on MasteringPhysics now!

12 Physics 201 p. 5/2 Homework assignments Homeworks will be found and submitted on MasteringPhysics. Register on MasteringPhysics now! Check carefully the due date and time.

13 Physics 201 p. 5/2 Homework assignments Homeworks will be found and submitted on MasteringPhysics. Register on MasteringPhysics now! Check carefully the due date and time. Look at the class homepage for policies concerning late homeworks.

14 Physics 201 p. 6/2 Behavior to avoid in class Surf the Web

15 Physics 201 p. 6/2 Behavior to avoid in class Surf the Web Private chats

16 Physics 201 p. 6/2 Behavior to avoid in class Surf the Web Private chats Entering and leaving class at inappropriate times

17 Physics 201 p. 6/2 Behavior to avoid in class Surf the Web Private chats Entering and leaving class at inappropriate times Loud snoring (with nightmares)

18 Physics 201 p. 7/2 How to learn from the Textbook Work out the conceptual questions at the end of each chapter

19 Physics 201 p. 7/2 How to learn from the Textbook Work out the conceptual questions at the end of each chapter Work out extra problems (call beyond duty)

20 Physics 201 p. 7/2 How to learn from the Textbook Work out the conceptual questions at the end of each chapter Work out extra problems (call beyond duty) Learn the strategy of problem solving from Problem-Solving Summaries

21 Physics 201 p. 8/2 Length, Mass and Time: SI units Unit of length: meter (m) One ten-millionth of the distance between the North Pole and the Equator, two marks on a platinum-iridium rod in Paris. Distance traveled by light in vacuum in 1/299,792,458 of a second. 1 inch = 2.54 cm; 3.28 ft = 1 m

22 Physics 201 p. 9/2 Length, Mass and Time: SI units Unit of mass:kilogram (kg) Kilogram = mass of platinum-iridium cylinder kept outside Paris. Mass (intrinsic property) Weight (force due to gravity)

23 Physics 201 p. 10/2 Length, Mass and Time: SI units Unit of time: second (s) Earth rotation, etc... Most accurate: Atomic Clock (Cesium-133)

24 Physics 201 p. 11/2 Length, Mass and Time: SI units Typical distances

25 Physics 201 p. 12/2 Length, Mass and Time: SI units Typical masses

26 Physics 201 p. 13/2 Length, Mass and Time: SI units Typical times

27 Length, Mass and Time: SI units Common prefixes Keep your units straight! Physics 201 p. 14/2

28 Physics 201 p. 15/2 Dimensional Analysis Apples Oranges Position versus time: Is x = x 0 + vt 2 correct? x: distance [L] v: velocity (distance/time) [L]/[T] vt 2 : ([L]/[T ]) [T ] 2 = [L] [T ] Wrong Dimension

29 Physics 201 p. 15/2 Dimensional Analysis Apples Oranges Position versus time: Is x = x 0 + vt 2 correct? x: distance [L] v: velocity (distance/time) [L]/[T] vt 2 : ([L]/[T ]) [T ] 2 = [L] [T ] Wrong Dimension Correct dependence: x = x 0 + αvt. α: a dimensionless constant determined by physics. Let s check: [L] = [L] + ([L]/[T])[T] Correct!

30 Physics 201 p. 16/2 Significant Figures Significant Figure = Number of digits known with certainty

31 Physics 201 p. 16/2 Significant Figures Significant Figure = Number of digits known with certainty Example: x = 2.5m x is known to two significant figures.

32 Physics 201 p. 16/2 Significant Figures Significant Figure = Number of digits known with certainty Example: x = 2.5m x is known to two significant figures. Multiplication or Division: a b = c or a/b = c number of sig fig for c = number of sig fig of the least accurate of a or b. Same for more complicated expressions.

33 Physics 201 p. 16/2 Significant Figures Significant Figure = Number of digits known with certainty Example: x = 2.5m x is known to two significant figures. Multiplication or Division: a b = c or a/b = c number of sig fig for c = number of sig fig of the least accurate of a or b. Same for more complicated expressions. Addition or Subtraction: a + b = c or a b = c number of decimal places for c = number of decimal places of the least accurate of a or b

34 Physics 201 p. 17/2 Example The Coyote steadily sneaks upon the Roadrunner with a constant speed of 1.2 m/s. How much distance has he covered after 5.35 s? 1) 1.2m/s 5.4s = 6.48m 2) 1.2m/s 5.4s = 6.5m 3) 1.2m/s 5.35s = 6.42m 6.4m (1): Incorrect number of Sig Fig in the answer; Round-off error in the time

35 Physics 201 p. 17/2 Example The Coyote steadily sneaks upon the Roadrunner with a constant speed of 1.2 m/s. How much distance has he covered after 5.35 s? 1) 1.2m/s 5.4s = 6.48m 2) 1.2m/s 5.4s = 6.5m 3) 1.2m/s 5.35s = 6.42m 6.4m (1): Incorrect number of Sig Fig in the answer; Round-off error in the time (2): Correct number of Sig Fig in the answer but round-off error in the time

36 Physics 201 p. 17/2 Example The Coyote steadily sneaks upon the Roadrunner with a constant speed of 1.2 m/s. How much distance has he covered after 5.35 s? 1) 1.2m/s 5.4s = 6.48m 2) 1.2m/s 5.4s = 6.5m 3) 1.2m/s 5.35s = 6.42m 6.4m (1): Incorrect number of Sig Fig in the answer; Round-off error in the time (2): Correct number of Sig Fig in the answer but round-off error in the time (3): Everything is done correctly

37 Physics 201 p. 18/2 Scientific Notation Example: Speed of Light = 299, 792, 458 m/s. Known to 9 sig figs.

38 Physics 201 p. 18/2 Scientific Notation Example: Speed of Light = 299, 792, 458 m/s. Known to 9 sig figs. It can be written as m/s.

39 Physics 201 p. 18/2 Scientific Notation Example: Speed of Light = 299, 792, 458 m/s. Known to 9 sig figs. It can be written as m/s. One can write it as m/s if it is known to 2 sig figs.

40 Physics 201 p. 19/2 Change of unit Example: Kareem Abdul-Jabar is 7-foot-2. How tall is he in meters? Answer: 1) 2 in = 1/6 ft; 2) 7 foot ft = 7.16ft/3.28ft = 2.18m.

41 Physics 201 p. 20/2 Order-of-magnitude estimates How many grains of rice are there in the jar lying on that table in class?

42 Physics 201 p. 21/2 Problem Solving Read the problem carefully

43 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system

44 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process

45 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process Find a strategy

46 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process Find a strategy Find the appropriate equations

47 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process Find a strategy Find the appropriate equations Solve the equations

48 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process Find a strategy Find the appropriate equations Solve the equations Check your answer

49 Physics 201 p. 21/2 Problem Solving Read the problem carefully Sketch the system Visualize the physical process Find a strategy Find the appropriate equations Solve the equations Check your answer Limits and special cases