Wednesday, June 20, 2012

Cheetos as a Bullet Proof Vest

All Ralphie Parker wanted for Christmas was a Red Ryder, carbine-action, 200 shot range model air rifle. "You'll shoot your eye out" was all anyone ever replied. BB guns can be dangerous. Like Ralphie, dad received a Red Ryder BB gun when he was a kid. In this experiment we are going to test a way to make BB guns safer. We ask the question - how many Cheetos does it take to stop a BB?

For the first part of our experiment, we wanted to know how fast the BBs are traveling when shot. This would help us establish their momentum. (Momentum is velocity x mass.)

We thought of several ways we could test for the speed.
  • We could shoot the BB through two laser beams.
  • We could shoot the BB straight into the air and time how long it takes to land.
  • We could shoot a BB at a mobile police radar unit that warns drivers of their speed.
We decided that we could use sound instead. We measured 10 feet from a fence, then recorded shooting a BB at the fence.

We used a program called Audacity to measure the time difference between the sound of the gun firing and the sound of the BB hitting the fence. It was 0.07 seconds.

There are 5280 feet in a mile, so it would take a BB ((5280 / 10) * 0.07 = ) 36.96 seconds to go a mile. To get miles per house we take 60 seconds/minute * 60 mintues/hour  = 3600, and divide that by 36.96 seconds. The total (3600 / 36.96) is 97.4 miles/hour. 

A BB is 5.23 grains, which is .01 ounces.

Next, we pinched a row of Cheetos between two kabob skewers.  

 Then we attached the skewers onto the BB gun.


Then we fired a BB into the Cheetos.

We did the experiment twice. The first time, the BB went through 3 Cheetos and stopped at the 4th. The second time, the BB embedded itself in the middle of the 4th Cheeto.



Are you soon going to be able to go to Cabelas and buy a BB-proof vest made of Cheetos? Probably not. But Cheetos just might have protected Ralphie when he was firing his BB gun.

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