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Do Now

Do Now. If Olivia drives at 68 mph for 5 hours, how far did travel?

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Do Now

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  1. Do Now • If Olivia drives at 68 mph for 5 hours, how far did travel? • You really want to drive to visit the Heat’s science teacher Ms. Lusk over the summer break. She lives in Washington State! If you travel at 70 mph for 24 hours, would you make it to WA? Why or why not? (p.s. How far do you think Washington is? Think critically!!!)

  2. Announcements • Pre-Lab Sheets will be handed out today…due back tomorrow to participate in lab

  3. Velocity and Acceleration Speed it up!

  4. Velocity: What is it? • Velocity is aspeed in a specific direction. • Formula: v= d/t + direction • Examples of velocities: • 30 m/s to the left • 45 mi/hr west • 18 km/s up

  5. Velocity Example Problems • Mejde was taking a rocket ship to his home in outerspace. If the rocket travels 900 km in 2 minutes towards the sun, what is his velocity? • Ms. Britain is driving North to her parents’ home in New Hampshire. If she drives 720 miles for 12 hours, what is her velocity?

  6. REMEMBER!!!!!!! • Solve Velocity problems JUST LIKE SPEED problems. Just add in a DIRECTION.

  7. Speed and Velocity…. • http://www.youtube.com/watch?v=DRb5PSxJerM

  8. Acceleration • Acceleration is a change in velocity over time

  9. Check for Understanding What two components make up velocity?

  10. Check for Understanding Velocity Speed Direction

  11. Acceleration • Def.: Change in _________ over ___________ • Can be change in speed or direction • (speed up, slow down, or change direction)

  12. Acceleration • Def.: Change in _velocity_ over __time____ • Can be change in speed or direction • (speed up, slow down, or change direction)

  13. Check for Understanding Is this ball accelerating? Yes! Because the direction is changing.

  14. Which cars are accelerating? A B C Cars B and C!

  15. Acceleration Acceleration is not just a change in velocity, it’s how fast that change happens.

  16. Which car has the greatest acceleration? A B C Car C!

  17. Discovery Education Video • http://player.discoveryeducation.com/index.cfm?guidAssetId=A04DA40D-810B-4057-B333-7752AF27FAA2&blnFromSearch=1&productcode=US

  18. Acceleration To measure it, you must know the initial velocity, the final velocity, and the time it takes to make the change.

  19. Acceleration • Def.: Change in velocity • Can be change in speed or direction • (speed up, slow down, or change direction) • Acceleration = ∆v/ t

  20. Acceleration • Initial Velocity –Object’s velocity when you start measuring acceleration. • Final Velocity –Object’s velocity when you finish measuring acceleration. •  - Greek letter delta – “change”

  21. Acceleration The unit for acceleration is m/s2. Acceleration = change in velocity time  v a = t

  22. Acceleration v is the difference between the final velocity (vf) and the initial velocity (vi). v = vf- vi

  23. Acceleration • Def.: Change in velocity • Can be change in speed or direction • (speed up, slow down, or change direction) • Acceleration = ∆v/ t • ∆v = vf – vi

  24. Example 1 • A roller coaster’s velocity at the top of a hill is 10m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26m/s. What is the acceleration of the roller coaster?

  25. Answer • vf = 26 m/s vi = 10 m/s t = 2 s • Acceleration = ∆v/ t • a = 26m/s – 10m/s 2 s a = 16m/s 2s a = 8m/s/s or 8m/s2

  26. Examples 2-4 – Try them! 2. A car travels at 60 miles per hour around a curve. Is the car accelerating? 3. A car travels in a straight line at 60 mi/hr. Is the car accelerating? 4. A car goes from 0 mph to 60 mph in 6 seconds. What’s the car’s acceleration?

  27. Answers: 1. Yes! Because it’s changing direction. 2. No! It’s not changing speed or direction. 3. -vf = 60 mph vi = 0 mph t = 6 s -a = vf – vi t -a = 60 – 0 mph = 10 m/s2 6 s

  28. Graphing Velocity vs. Time Constant acc. No acc. Increasing acc.

  29. Exit Ticket • What is the unit of acceleration? • Solve these problems: • A car is traveling at a velocity of 24 km/hr west and increases to a speed of 50 km/hr west in 4 seconds. What is the car’s acceleration? • Jada is walking to the store at a velocity of 5 km/hr. She realizes that the store is closing in a few minutes. She accelerates to running at a rate of 15 km/hour in 2 seconds. What is her rate of acceleration?

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