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What is Exciting About this Scene?

What is Exciting About this Scene?. http://www.youtube.com/watch?v=MlD5NBnzFhE. JTPS. What are 3 words that come to mind when you think about Motion?. Chapter 3. Linear Motion. Description of Motion. instantaneous speed - the speed that something has at any one instance.

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What is Exciting About this Scene?

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  1. What is Exciting About this Scene? http://www.youtube.com/watch?v=MlD5NBnzFhE

  2. JTPS What are 3 words that come to mind when you think about Motion?

  3. Chapter 3 Linear Motion

  4. Description of Motion • instantaneous speed - the speed that something has at any one instance

  5. The average speed for a trip might be 53 miles/hour. However, during this trip your instantaneous speed might have been 0 miles/hour at a stoplight... ...or 70 miles/hour on the open road.

  6. White Board Question • 1. What is the average speed of a cheetah that sprints 100 meters in 4 seconds? • 2. How about if it sprints 50 m in 2 s?

  7. What are the units of speed? • miles/hour…………….mph • kilometer/hour……….km/h • meters/second……….m/s • furlongs/fortnight?

  8. Example Question • If a car moves with an average speed of 60km/h for an hour, it will travel a distance of 60 km. • (a) How far would if travel if it moved at this rate for 4 hours? • (b) For 10 h? • (c) Would it be possible for the car to have an average speed of 60km/h and never exceed a reading of 60km/h?

  9. Velocity Velocity = {speed with a direction} Examples: 70 mph is a speed. 70 mph North is a velocity.

  10. Acceleration • Acceleration - rate of change in velocity due to change in speed or direction • Example: • 9.8 meters/second2 downward

  11. White Board Question • "She moves at a constant speed in a constant direction.” • Say the same sentence in fewer words. • Answer: “She moves at constant velocity.”

  12. White Board Question • The speedometer of a car moving to the east reads 100km/h. • It passes another car that moves to the west at 100km/h. • Do both cars have the same speed? • Do they have the same velocity?

  13. White Board Question • During a certain time, the speedometer of car reads a constant 60km/h. • Does this indicate a constant speed? • Constant velocity?

  14. Example Multiple-Choice Questions1. The two measurements necessary for calculating average speed are (a) acceleration and time. (b) velocity and time. (c) distance and time. (d) distance and acceleration.

  15. 2. What is the average speed of a horse that gallops a distance of 10 kilometers in a time of 30 minutes? (a) 10km/h (b) 20km/h (c) 30km/h (d) more than 30km/h

  16. 3. What is the acceleration of a car that maintains a constant velocity of 100km/h for 10 seconds? (a) 0 km/h s (b) 10 km/h s (c) 10 m/s2 (d) 1000 km/h s

  17. Distance VS. Time The slope of the distance-time graph is the velocity Changing Velocity Constant Velocity

  18. Velocity VS. Time The slope of the velocity-time graph is the acceleration. Changing Acceleration Constant Acceleration

  19. Depicting Motion How To Graphically Represent Linear Motion

  20. Coordinate System • Coordinate System- Deciding where to place the measuring tape and when to start the timer. • Origin- Point where both variables are of value zero.

  21. Problem Solving • Follow these steps to solve problems: • Read Problem • Make Diagram • Identify Knowns • Identify Unknowns • Choose Formula • Solve (and Check) • Acronym R.D. KUFS (Mr. Hairston’s Rap Alias)

  22. Practice Drawing Motion • A bike travels at a constant speed of 4.0 m/s for 5 s. How far does it go?

  23. Practice Drawing Motion • A bike accelerates from 0.0 m/s to 4.0 m/s in 4 s. What distance does it travel?

  24. Practice Drawing Motion • A bike first accelerates from 0.0 m/s to 5.0 m/s in 4.5s. What is the acceleration of the bike?

  25. White Board Question • A car travels southeast at 83 m/s. How long will it take the car to travel 633 m?

  26. Describing Motion: The Kinematic Equations DISCOVERING THE UNKNOWN

  27. Kinematic Equations d = displacement vi = initial velocity vf = final velocity a = acceleration t = time

  28. R.D. KUFS • A truck having an initial velocity of 30 m/s accelerates uniformly at +3 m/s2. • What is its velocity after 4 seconds? • How far has it traveled in 4 seconds? • c) How fast is it moving after it has traveled 100 m from its original position? • How long did it take to travel the 100 m?

  29. Practice Problem Solving • Ima Hurryin is approaching a stoplight moving with a velocity of +30.0 m/s. The light turns yellow, and Ima applies the brakes and skids to a stop. If Ima's acceleration is negative (-)8.00 m/s2, then determine the displacement of the car during the skidding process. (Note that the direction of the velocity and the acceleration vectors are denoted by a (+) and a (–) sign). • 56.3 m

  30. Practice Problem Solving • Ben Rushin is waiting at a stoplight. When it finally turns green, Ben accelerated from rest at a rate of a 6.00 m/s2 for a time of 4.10 seconds. Determine the displacement of Ben's car during this time period. • 50.4 m

  31. Free Falling What will you do when there’s nothing holding you back?

  32. Free Fall • An object is in free fall when the only force acting on it is the force of gravity • The force of gravity points downward • Acceleration due to gravity is 9.8m/s2 • Air resistance ignored

  33. An Object In Free Fall • To a physicist, the term "free fall" has a different meaning than it does to a skydiver. In physics, free fall is the (one-dimensional) motion of any object under the influence of gravity only - no air resistance or friction effects of any kind, whereas it is air resistance that makes skydiving a hobby rather than a suicide attempt!

  34. An Object In Free Fall • You should also note that an object doesn't have to be falling to be in free fall - if you throw a ball upward its motion is still considered to be free fall, since it is moving under the influence of gravity. 

  35. Free Fall • An object is in free fall when the only force acting on it is the force of gravity • The force of gravity points downward • Air resistance ignored • Acceleration due to the force of gravity near the surface of Earth is downward and has a value of g = 9.8 m/s2 (note: g is just the magnitude of the objects acceleration) • We have then the conditions of one-dimensional kinematics – straight line motion with constant acceleration.

  36. For Free Fall... (a) you drop an object from rest at t=0. (b) velocity acquired = acceleration ´ time v = g t (c)

  37. 6. Dan drops a stone down a well and sees it hit the water 4 seconds later. Neglecting air resistance, how deep is this well?(a) 9.8 m (b) 19.6 m (c) 78.4 m (d) 156.8 m (e) 39.2 m

  38. 7. Dan drops a stone down a well and sees it hit the water 4 seconds later. Neglecting air resistance, what is the speed of impact of the stone? (a) 9.8 m/s (b) 19.6 m/s (c) 4.9 m/s (d) 78.4 m/s (e) 39.2 m/s

  39. Sample Problem • A ball is thrown vertically upward at 10 m/s. How high will it get, how long will it be in the air, and how fast will it be moving when it hits the ground.

  40. Velocity = {speed with a direction}

  41. g = 9.8 m/s2 downward

  42. Kinematic Equations d = displacement vi = initial velocity vf = final velocity a = acceleration t = time

  43. Free Fall v = g t

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