Physics Week 2 2017 September 11 2017 Please

Physics Week 2 2017

September 11, 2017 Please take out homework and copy the daily objective onto your drill sheet. • Today I will take a quiz on graphing and mathematical models Get ready to tackle the drill!

Drill 9. 11 1. A ____ is an interaction between two objects that is capable of changing the motion of an object. 2. A physical quantity that specifies a direction is called _______ quantity. 3. Do you agree or disagree with the statement that a correctly made measurement should be exact. 4. What are the 4 components of a scientific explanation?

September 12, 2017 Please take out homework and copy the daily objective onto your drill sheet. • Today I will learn about describing motion in a straight line Get ready to tackle the drill!

Drill 9. 12 1. 2. 3. 4. Convert 45 millimeters to meters Convert 0. 85 kilograms to grams Convert 3. 8 x 1014 m. W to k. W Convert 35 mi/hr to m/s (1 mi=1. 6 km) 5. Estimate the mass of your phone in grams 6. Estimate the length of the Poly-Western campus in kilometers

Quiz Grades LM 1 (Linear Models 1: Scatter Plots) LM 2 (Linear Models 2: Line of Best Fit) LM 3 (Linear Models 3: Mathematical Model) Novice = 0/5 = no evidence Developing = 2/5 = some evidence Satisfactory = 4/5 = missing some details Expert = 5/5 = pretty much perfect

Turn & Talk You want to make plans to study with a friend later this week. What information must be communicated in order to make that happen?

September 13, 2017 Please take out homework and copy the daily objective onto your drill sheet. • Today I will investigate the motion of a battery powered car and develop a mathematical model to describe its motion Get ready to tackle the drill!

Drill 9. 13 1. Give 3 examples of vector quantities. 2. Give 3 examples of scalar quantities. 3. What to vector and scalar quantities have in common? 4. How are they different? Before a Ravens game you walk 7 blocks east to get chips and salsa at the store, then walk 4 blocks west to your friend’s house where you are going to watch the game. 5. How far did you walk? (distance) 6. What was your total displacement?

Position • Location of an object in a coordinate system. • A coordinate system must have an origin and an orientation. • You can identify position by specifying how far the object is from the origin and in what direction. • Symbol: x Units: m • Is position a vector quantity?

Displacement • Is defined as change of position. • How far & in what direction from starting point. • Symbol: Dx = x 2 -x 1 Units: meters

Distance • Describes how far something moves • Symbol: d Units: meters • What is the displacement of an object that starts at x=12 m and ends at x=7 m? • If you don’t change direction distance equals the absolute value of displacement. • If direction changes add up the individual distances (draw a diagram!)

September 14, 2017 Please take out homework and copy the daily objective onto your drill sheet. • Today I will learn about speed and velocity and will build a consensus understanding of the toy car investigation Get ready to tackle the drill!

Drill (9. 14) 1. Write down the following quantities and identify each as a vector (V) or a scalar (S) 55 mph 15 meters south 2. 0 L 19. 6 N down 2. What is the magnitude of each of the quantities in question 1? During a punt return, the receiver has to drop back from the 20 yard line to the 5 yard line to field the ball. His teammates make some excellent blocks as he returns the ball straight up the field to the 35 yard line before getting tackled. 1. How far did the punt returner travel during the play? 2. What was the his displacement?

Speed • Scalar quantity describing how fast something is moving • symbol: v SI units: m/s • Relationship: average speed = distance/time v = d/t

Example 1 It takes a student 25 seconds to walk 75 feet east down the hallway. What is their average speed? t=25 s v=? d=75 ft v=d/t =75 ft / 25 s = 3. 0 ft/s

Example 2 Usain Bolt runs at an average speed of 10. 4 m/s during a 100 meter race. How long does it take him to complete the sprint? v=10. 4 m/s d=100 m t=? v=d/t t=d/v =(100 m)/(10. 4 m/s) = 9. 6 m x s/m = 9. 6 s

Velocity • Vector quantity describing both speed and direction • Rate that position is changing • Symbol: v SI units: m/s • Relationship: avg velocity = displacement/time vavg=Dx/t

Example 3 It takes a student 25 seconds to walk 75 feet east down the hallway. What is their average velocity? t=25 s v=? Dx=75 ft east v=Dx/t =(75 ft east)/ 25 s = 3. 0 ft/s east When an object does not change direction the magnitude of the displacement equals the distance and the magnitude of the average velocity equals the average speed.

Example 4 A car drives 120 miles east in 2 hours, then drives 90 miles west in 3 hours. What is their average velocity? 120 mi Dx=30 mi east vavg=? 90 mi t=2 h + 3 h = 5 h vavg=Dx/t = (30 mi east)/(5 h) = 6 mi/h east

Poster/Whiteboard “look-fors” 21 • GRAPH (SKETCH) • MATHEMATICAL MODEL • INTERPRETATION http: //modeling. asu. edu/modeling/ Malcolm. Wells_7 min. MOV

Acceleration • Acceleration is a vector quantity that describes how quickly the velocity of an object is changing • Symbol: a SI units: (m/s) per s or m/s 2 • Relationship: average acceleration = amount velocity changed how long it took aavg=Dv/Dt

Example 5 What is the acceleration of a car that travels east at a constant speed of 60 mi/h for 3 h? Answer: ZERO!! Acceleration describes how quickly velocity is changing and neither the magnitude or direction of this car’s velocity are changing.

September 15, 2017 Please take out homework and copy the daily objective onto your drill sheet. • Today I will develop the constant velocity model Get ready to tackle the drill!

9. 15 Drill Fill in the blanks with the appropriate vocabulary term. 1. The study of motion is called _________. 2. Quantities which have both a magnitude and a direction are called _________. 3. ______ is a scalar quantity that describes how far something has traveled. 4. _______ is a vector quantity that describes the location of an object in a coordinate system. 5. _______ describes how fast an object is moving and in what direction. 6. ______ describes how quickly an object’s velocity is changing.

Application Starting from the origin a rabbit hops 35 yards north in 22 seconds then hops 65 yards south in 38 seconds. 1. What is the rabbit’s total displacement? 2. What is the total distance traveled by the rabbit? 3. What is the rabbit’s average speed? 4. What is the rabbit’s average velocity?

• Total time = 22 s + 38 s = 60 s • Distance = 35 yds + 65 yds = 100 yds • Displacement = 30 yds south • Avg Speed = dist/time = 100 yds/60 s = 1. 67 yds/s • Avg velocity = displacement/time = 30 yds south/60 s =0. 5 yds/s south 35 yds 65 yds

Turn & Talk What does the slope of our linear models tell us about the motion of the toy car? What does the y-intercept tell us? Would all types of motion result in a linear relationship between position & time?

Constant Velocity Particle Model • Applies to an object that travels at a constant speed in a straight line. • Graph of position vs. time is linear • Slope of position vs. time indicates velocity • Y-intercept indicates initial position • x = v t + xo • Dx=vt • v=d/t

Constant Velocity Model CV 1 Determine the total distance, total displacement, average speed, and average velocity of an object moving along a straight line. (There may be more than one segment to the motion, but the velocity of the object is constant for each segment). CV 2 Solve algebraic problems using the constant velocity model. x=vt + xo or v=d/t Describe constant velocity motion with words, motion maps, position versus time graphs, and velocity versus time graphs. Correctly answer questions about the motion based on any of these representations. Given one representation, describe the motion with any of the other three. CV 3

Questions: • What similarities are evident when you look at all of the boards? What differences strike you? • What are alternative explanations? In what ways does the evidence limit the strength of your conclusions? • What type of mathematical relationship exists between the variables? If the relationship is linear, what is the significance of the slope? The yintercept? • What are the limitations of the model? When is it valid and when is it not? Language frames • • • “I really like _______ on that board because …” “I disagree with what _______ said because…. ” “I think that board could be improved by …. . . ” “I am still feeling confused about ………. ” “I am wondering about ……” “Do you agree that…. ” “I think it means ______ because…. . ” “What puzzles me is…. . ” “How would the results change if…. ? ”

“Board Meeting” guidelines 32 • Participants should not… • • • Present what is on their own boards Be rude or interrupt Criticize people • Participants should… • • Ask questions Provide supporting evidence and reasoning Critically evaluate ideas and reasoning Work toward consensus understanding • Observers should… • • Listen carefully Note positive contributions Reflect on how the conversation might be improved Be prepared to share observations