Aerodynamic Drag

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Aerodynamic Drag
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A Mystery (or is it?)

• You calculate that your rocket is going to go 2
  miles into the air but it only goes a few hundred
  feet
• WHY?
• Answer Drag acted against the rocket.

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What is Drag?

• An aerodynamic force that acts opposes motion of
  an object through the air
• Generated by all the parts that come in contact
  with the air

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What is Drag?

• Object has to be in contact with the air (or
  fluid that the object is passing through)
• If there is no fluid - then there is no drag.

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What do you need to have drag?

• Motion between the rocket and the air
• Is drag a force?
• Yes
• What direction does drag act?
• Opposite to the rockets motion.

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What can cause drag?

• Friction between the rocket and the air molecules
• The magnitude can depend on the properties of the
  rockets skin and the properties of the air

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What can cause drag?

• What does that mean?
• High density air more drag
• Rough finish on rocket more drag.

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Rocket Velocity versus Drag

• What do you think happens when the velocity of
  your rocket increases?
• Drag goes up (way up)
• Why?
• More air molecules to push out of the way per
  unit of time

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Is Drag a bad thing?

• Think about how the parachute uses drag.

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Drag

• Factors That Affect Drag
• Shape Effects On Drag
• Size Effects On Drag
• Inclination Effects On Drag
• Drag Equation
• Drag Coefficient

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Summary of Drag

• Factors That Affect Drag
• Shape Effects On Drag
• Size Effects On Drag
• Inclination Effects On Drag
• Drag Equation
• Drag Coefficient

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Aerodynamic Drag Quiz
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Quiz Question 1

• What is drag?

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Quiz Question 2

• What causes drag?

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Quiz Question 3

• What factor(s) influence the strength of drag?

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Quiz Question 4

• What can you do in the design and construction of
  a rocket to minimize drag?

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Quiz Question 5

• How can the magnitude of drag be determined?

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Quiz Question 6 (bonus)

• What is the formula for calculating drag?

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To Learn More

• http//www.grc.nasa.gov/WWW/K-12/airplane/shortr.h
  tml