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Average vs. Instantaneous speed

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Average vs. Instantaneous speed

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    1. Average vs. Instantaneous speed Average speed is the distance traveled divided by the time to travel. Instantaneous speed is the average speed for infinitely small distances and times.

    3. These plots are v vs t graphs of the d vs t graphs from the previous slide.

    4. Fall 2004 Data

    5. Which v vs t Graph Corresponds to the Given d vs t Graph?

    6. Which v vs t Graph Corresponds to the Given d vs t Graph?

    7. Which v vs t Graph Corresponds to the Given d vs t Graph?

    8. Which v vs t Graph Corresponds to the Given d vs t Graph?

    9. Price rise

    10. What about the direction? Airplanes Speed is how fast is something going. Speed = distance crossed / time elapsed Velocity is the speed and direction of an object. Velocity is a vector (has magnitude and direction). Speed is a scalar (has magnitude only)

    11. Speed and Velocity Moving all the time equally fast (with respect to the ground)? Constant speed Moving all the time equally fast and also in the same direction? Constant velocity Do we always move equally fast? Do we always move in the same direction?

    12. Average and Instantaneous Speed Trip from home to school

    13. Average and Instantaneous Speed

    14. Average Velocity

    15. Average and Instantaneous Velocity

    16. Displacement vs Distance

    17. Reminder (Previous cycle): Distance and Displacement

    18. Distance and displacement Distance and displacement are two quantities which may seem to mean the same thing, yet have distinctly different definitions and meanings. Distance is a scalar quantity (has magnitude only) which refers to "how much ground an object has covered" during its motion. Displacement is a vector quantity (has magnitude and direction) which refers to "how far out of place an object is"; it is the object's change in position. http://www.glenbrook.k12.il.us/gbssci/phys/Class/1DKin/U1L1c.html

    19. Direction of the Average Velocity

    20. Direction of the Average Velocity

    21. The Slope of a Distance vs Time Graph is Velocity Remember! So, if Distance is graphed on the y-axis and Time is graphed on the x-axis, the Slope,

    22. Mystery Walk 1 Write a description of this walkers motion.

    23. Mystery Walk 1 Write a description of this walkers motion.

    24. More Mystery Walk 1 Now Sketch a velocity vs time graph for Mystery Walk 1.

    25. Velocity vs Time Graph Walk 1

    26. Mystery Walk 2 Based on the graph, describe what the walker did.

    27. Mystery Walk 2 He waited for 4 seconds before starting to walk slowly with a step size of 0.5. He walked for a few seconds and then stopped.

    28. Mystery Walk 2 Now, sketch a velocity time graph of Mystery Walk 2.

    29. Mystery Walk 2 Velocity vs Time Graph

    30. Mystery walk 2

    31. Mystery Walk 3 Based on the graph describe what the walker did during her walk.

    32. Mystery Walk 3 She walked backward very slowly. After 5 seconds, she ran forward for 5 more seconds.

    33. Mystery Walk 3 Sketch a Velocity vs Time graph of Mystery Walk 3.

    34. Velocity vs Time for Mystery Walk 3

    35. Mystery walk 3

    36. Make sense Quantities needed to describe motion: The distance traveled divided by the time to travel: Average speed The average speed for infinitely small distances and times: Instantaneous speed Speed and direction: Velocity Constant speed vs. constant velocity?

    37. Make sense: Velocity and speed How would you determine the average speed of an object on these paths:

    38. Velocity is a vector Velocity is a vector Vectors are quantities that have magnitude and direction Speed is the magnitude of a velocity.

    39. Average vs. Instantaneous Velocity

    40. Do the runners have the same average velocities? How do you know?

    41. Where do the runners ever have the same instantaneous velocity? How do you know?

    42. ACCELERATION Acceleration (a) is the ratio of change in velocity to change in time It is a vector quantity like displacement and velocity. It can be + or -. Formula for average acceleration a = ?velocity (v) = v -vo time (t) t - to the units for a are m/s2

    43. The Slope of an Velocity vs Time Graph is Acceleration If Velocity is graphed on the y-axis and Time is graphed on the x-axis, the slope of the graph

    44. ACCELERATION 1. The slope of a velocity-time graph is acceleration just as the slope of a displacement-time graph is velocity. No slope. No acceleration. a. If the graph is linear, acceleration is uniform or constant and avg. acceleration = instantaneous acceleration. b. If the graph is a curve. The acceleration is different at every point, but instantaneous acceleration on this graph is still the slope at a point on the curve.

    45. Remember! Acceleration is a Vector This means that it can have a sign (+ or -). So, a velocity vs time graph with a positive slope is a (+) acceleration graph and a velocity vs time graph with a negative slope is a deceleration graph.

    46. Graphing (+) & (-) Acceleration

    47. Why is it + Acceleration?

    48. Why is it () Acceleration?

    49. Why is there no Acceleration?

    50. Graphing the motion of a Ball thrown Upward

    51. Breaking Down the Throw: Acceleration of the Upward Leg

    52. Breaking Down the Throw: Acceleration of the Downward Leg

    53. Position vs Time Graph of Constant Positive (+) Acceleration

    54. Position vs Time Graph of Constant Positive Negative (-)Acceleration

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