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Period 1

Period 1. Pg. 29-31 Ques : 27, 33, 36, 56, 58a, 60-62, 66, 68b. Warm-Up Questions. Just think, what is the difference between… Speed & Velocity? Distance & Displacement. 1-Dimensional Motion. Motion…(in a straight line). An object is in motion if…

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Period 1

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  1. Period 1 • Pg. 29-31 • Ques: 27, 33, 36, 56, 58a, 60-62, 66, 68b

  2. Warm-Up Questions • Just think, what is the difference between… • Speed & Velocity? • Distance & Displacement

  3. 1-Dimensional Motion

  4. Motion…(in a straight line) • An object is in motion if… …it changes position …or… travels a distance • How do we typically describe motion? • Speed • Units…?? • Distance & Time -- Equation??

  5. Speed vs. Velocity • What’s the difference? • Speed = • Velocity = • Difference btwn. Distance & displacement then? • Dist = total path length an object covered during its motion • Disp = directional distance between an object’s starting and ending points of motion -- Velocity Equation???

  6. Scalar vs. Vector Quantities • Scalar • Quantities that are described by magnitude alone • Vector • Quantities that are described by BOTH a magnitude and direction

  7. Examples: Scalar or Vector?? • Distance = _______ • Displacement = _______ • Time = _______ • Mass = _______ • Velocity = _______ • Speed = _______ • Acceleration = _______

  8. Vector Addition • A vector is represented by an arrow • Drawn to scale and points in the direction of the motion • NET outcome = resultant vector ***Sum all the vectors in x direction & sum all vectors in y direction, then find magnitude of resultant vector • Example: • A car drives 5 km east, stops, and drives another 3 km east. Draw the 2 initial vectors and the resultant vector.

  9. Vector Addition • A vector is represented by an arrow • Drawn to scale and points in the direction of the motion • NET outcome = resultant vector • Example: • A car drives 2 km east, stops, drives 10 km west, stops, and then drives another 3 km east again. Draw the 3 initial vectors and the resultant vector.

  10. ***Need to Know Equations*** • Avg. Speed = • Avg. Velocity = • Final Position =

  11. Question… • A hiker walks 6 km west and then turns abruptly and immediately walks another 8 km north and stops to catch his breath. • What was the distance that he hiked so far? • What was the displacement of his hike so far?

  12. Use Trig to find Direction • A hiker walks 6 km west and then turns abruptly and immediately walks another 8 km north and stops to catch his breath. • What was the displacement of his hike so far?

  13. **Circumference = 2 r ** Question • A BPHS track star runs the 100 m turn (half circle portion at the end of the track) in 16 s. • What distance did they run? Displacement? • What was their speed? Velocity?

  14. Warm-Up Question • A jogger jogs 300 m straight in one direction in 2.5 min and then jogs back to the starting point in 3.3 min. What was the jogger’s avg velocity: • On the way down? • On the way back to the starting point? • For the total jog?

  15. Distance vs. Displacement Wkst

  16. Instantaneous Velocity • Defined as: • How fast something is moving in which direction at a particular instant of time • When dealing with uniform motion, how are inst. velocity and avg. velocity related?

  17. Graphical Representation

  18. Nonuniform Motion • How would you find the inst. velocity of an object’s motion that looked like: Position Time

  19. Nonuniform Motion • How would you find the inst. velocity of an object’s motion that looked like:

  20. Nonuniform Motion • How would you find the inst. velocity of an object’s motion that looked like:

  21. Math Problems • Book: • Pg. 60-61 -> 1, 7, 8, 10, 13-14, 16, 21, (22 = Bonus)

  22. Acceleration • Defined as: • Rate at which velocity changes • Velocity changes when: • An object speeds up or slows down • An object changes its direction of motion • So when does an object accelerate?

  23. ***Need to Know Equations*** • Avg. Acceleration = • Final Velocity (w/ constant acceleration) =

  24. Acceleration Math • A car has an initial velocity of 80 m/s. It slows down to a stop in 8 seconds. What was the cars acceleration during this time?

  25. Average Velocity Question… • What was the average velocity of that car as it constantly accelerated during that time period?

  26. ***Need to Know Equations*** • Avg. Acceleration = • Final Velocity (w/ constant acceleration) = • Avg. Velocity (w/ constant acceleration) =

  27. Math Problems • Pg. 61-62  23-27, 30, 32-34

  28. Kinematic Equations • Some physics problems are hard to do because they require the application of multiple equations throughout one question. • How can we make our lives easier…? • Let’s combine a couple of our equations algebraically in advance

  29. Deriving Equations • Final position w/o avg. velocity & acceleration: • Xfeq: • Avg. V eq: • Combined (sub in for avg. v):

  30. Deriving Equations • Final position w/o avg. velocity & acceleration: xf = xi + ½(vf + vi)t

  31. Deriving Equations • Displacement when object accelerates w/o vf:

  32. Deriving Equations • Displacement when object accelerates w/o vf: • Use previous equation: • Vfeq: • Combined (sub in for Vf):

  33. Deriving Equations • Displacement when object accelerates w/o vf: xf = xi + vit + ½at2

  34. Deriving Equations • Displacement when object accelerates from rest: xf = xi + vit + ½at2 xf = xi + ½at2 xf = ½at2

  35. Deriving Equations • Displacement, Velocity, & Acceleration w/o Time: • Use Vfeq: • xf = xi + ½(vf + vi)t eq:

  36. Deriving Equations • Displacement, Velocity, & Acceleration w/o Time:

  37. Deriving Equations • Displacement, Velocity, & Acceleration w/o Time: vf2= vi2 + 2a(xf – xi)

  38. Example Math Problem A rocket is shot horizontally from a soldier’s rocket launcher with a constant acceleration of 20m/s2. After 10 seconds, how fast is the rocket moving & how far has it traveled?

  39. Example Math Problem A rocket is shot horizontally from a soldier’s rocket launcher with a constant acceleration of 20m/s2. After 10 seconds, how fast is the rocket moving & how far has it traveled?

  40. Math Problems • Pg. 62  38 - 42

  41. Additional Lab Questions • What should the slope of the line for the graph that you drew be equal to? (Name & Value…think about rise over run) • Knowing this, what equation can we then derive to solve for the acceleration of an object on an inclined plane? • What was the percent error between the extrapolated value and the accepted value of g?

  42. Free Fall • Defined as: • When an object in motion is influenced only by the pull of gravity • Value of Gravity = - 9.8 m/s2

  43. Gravity • Does the acceleration of an object due to gravity ever change? • Acceleration due to g is constant! • Constant acceleration = which equations??? • Can it be different in different regions on Earth? • YES! Due to…. • Distance from Earth’s center • Air resistance

  44. Free Fall Equations

  45. Math Problems • Pg. 63-64  59-62, 64-67, 70a

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