StefanJ
Well-Known Member
- Joined
- Jul 6, 2009
- Messages
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Sometimes I write things in my head on long car trips.
On the way down to Eugene, OR for the Mini Maker Faire on Saturday, I worked through a lesson plan that teaches the background to stability with a filing card, a ruler, a penny, and some tape.
You can demonstrate the concept of center of gravity with the ruler. Same amount of mass on either side of the 6" line, and that's where it balances.
Center of pressure, you can show with the index card. Same amount of resistance to air on either side of the center line, and when you drop it, it tends to flutter down around this center.
From there, you modify your instruments. Tape a penny to various points of the ruler. Bend back flat the corners of the index card, reducing the air resistance on one end. Show how this changes the mass balance point of the ruler, and the aerodynamic balance point of the card . . . you can now throw the card!
Then combine things. Tape the penny to the center of the card and throw it. Move it up toward the folded-over ends (changing the center of mass) and throw it again.
I think you get the picture. If anyone is itnerested I could write this up more formally.
On the way down to Eugene, OR for the Mini Maker Faire on Saturday, I worked through a lesson plan that teaches the background to stability with a filing card, a ruler, a penny, and some tape.
You can demonstrate the concept of center of gravity with the ruler. Same amount of mass on either side of the 6" line, and that's where it balances.
Center of pressure, you can show with the index card. Same amount of resistance to air on either side of the center line, and when you drop it, it tends to flutter down around this center.
From there, you modify your instruments. Tape a penny to various points of the ruler. Bend back flat the corners of the index card, reducing the air resistance on one end. Show how this changes the mass balance point of the ruler, and the aerodynamic balance point of the card . . . you can now throw the card!
Then combine things. Tape the penny to the center of the card and throw it. Move it up toward the folded-over ends (changing the center of mass) and throw it again.
I think you get the picture. If anyone is itnerested I could write this up more formally.