Acceleration notes

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Acceleration notes

  1. 1. Good Morning <ul><li>You may sit anywhere in the FIRST THREE ROWS </li></ul><ul><li>Today you will need: </li></ul><ul><ul><li>lab book, calculator, spiral, pen or pencil </li></ul></ul><ul><li>Please do now: </li></ul><ul><ul><li>get your lab book, get out your calculator or borrow one, get out something to write with </li></ul></ul>
  2. 3. DIY Science Lab <ul><li>Using the motion detector, the laptop, and the Logger Pro software, figure out a way to create the following four graphs by your own motion. </li></ul>
  3. 4. DIY Science Lab <ul><li>Be sure to describe what motion you made in your lab book next to the corresponding graph! </li></ul>
  4. 5. Acceleration <ul><li>Acceleration </li></ul><ul><ul><li>a change in the velocity of an object </li></ul></ul><ul><li>Acceleration can be written as a formula </li></ul>a = Δ Δ v t
  5. 6. Acceleration <ul><li>A helpful way to think of acceleration is to say </li></ul><ul><ul><li>“acceleration is how fast the velocity changes” </li></ul></ul><ul><li>What is velocity? </li></ul><ul><ul><li>speed with a direction </li></ul></ul>
  6. 7. Velocity is a Vector Quantity <ul><li>A Vector quantity is something that has both a </li></ul><ul><ul><li>magnitude (size) </li></ul></ul><ul><ul><li>direction </li></ul></ul><ul><li>Is acceleration a vector quantity? </li></ul><ul><ul><li>YES! </li></ul></ul><ul><li>Speed is a SCALAR quantity – scalar quantities have only a size </li></ul>
  7. 8. Acceleration <ul><li>The fact that acceleration has both a speed and a direction component is important – it means that there are three ways an object can accelerate </li></ul><ul><ul><li>speed up </li></ul></ul><ul><ul><li>slow down </li></ul></ul><ul><ul><li>change direction </li></ul></ul><ul><li>Of course, an object can both speed up and change direction – or slow down and change direction </li></ul>
  8. 9. Acceleration and the Moving Man <ul><li>In the Moving Man simulation, we looked at the shape of graphs when the man was speeding up and slowing down. </li></ul><ul><li>In physics, we use the phrase “positive acceleration” to mean an increase in speed </li></ul><ul><li>What phrase we use for a decrease in speed? </li></ul><ul><ul><li>negative acceleration </li></ul></ul>
  9. 10. Acceleration and Formulas <ul><li>We’ve looked at ways to calculate acceleration using the formula </li></ul>
  10. 11. Acceleration Sample Problem <ul><li>A car is traveling at a speed of 45 km/h and then increases its speed to 75 km/h. The change in velocity takes 6 seconds. What is the acceleration? </li></ul>
  11. 12. Acceleration and Strobe Photos <ul><li>We’ve used three methods to describe constant velocity: </li></ul><ul><ul><li>graphs </li></ul></ul><ul><ul><li>formulas </li></ul></ul><ul><ul><li>strobe photos </li></ul></ul><ul><li>Strobe Photos can be used to describe acceleration as well </li></ul>
  12. 13. Acceleration and Strobe Photos <ul><li>Predict what the strobe photos for a car accelerating to the left would look like on the flipchart </li></ul>
  13. 14. Acceleration and Strobe Photos <ul><li>Because speed is changing when a car positively accelerates, the distance between the cars will increase with each photo. </li></ul><ul><li>REMEMBER: the photos are taken at equal time intervals, so this type of strobe shows a car traveling a greater and greater distance each second. </li></ul>
  14. 15. Motion and Graphs Review <ul><li>On your guided notes sheet (handout), predict what an automobile at rest would look like as a graph for: </li></ul><ul><li>dist v time </li></ul><ul><li>velocity v time </li></ul><ul><li>acceleration v time </li></ul>
  15. 16. Motion and Graphs Review <ul><li>On your guided notes sheet (handout), predict what an automobile at a constant velocity would look like as a graph for: </li></ul><ul><li>dist v time </li></ul><ul><li>velocity v time </li></ul><ul><li>acceleration v time </li></ul>
  16. 17. Motion and Graphs Review <ul><li>On your guided notes sheet (handout), predict what an automobile that is accelerating would look like as a graph for: </li></ul><ul><li>dist v time </li></ul><ul><li>velocity v time </li></ul><ul><li>acceleration v time </li></ul>

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