We take this as pretty solid evidence that R must be his Dad's son. And of course, when K came downstairs, she made one too!
Maybe for our next project we'll make our own arc-welding kit?
Sunday, February 21, 2010
A typical Sunday morning...
Dad's cooking up some bacon, Mom's still dozing with K. What better time to make your own welding mask?
We take this as pretty solid evidence that R must be his Dad's son. And of course, when K came downstairs, she made one too!
Maybe for our next project we'll make our own arc-welding kit?
We take this as pretty solid evidence that R must be his Dad's son. And of course, when K came downstairs, she made one too!
Maybe for our next project we'll make our own arc-welding kit?
Friday, February 19, 2010
So it's (still) the middle of winter and you need some music...
...what else would you do, but build your own resonance tube?
It's Dad, again. This time we decided to work on a project that was similar to a demonstration we saw put on by a group from the U of M called the Physics Force. It's a demonstration showing how heat can produce a standing wave in a cylinder. This kind of device is commonly referred to as a "hoot tube", but is more formally known as a Rijke tube, after its discoverer/inventor. Click here for a nice description of how it works.
The sound produced by our 5 foot long, 4 inch diameter tube (I mistakenly said it was 5 inches in the video) is about 101 Hz, based on the following approximation for the resonant frequency of an open cylinder (that is, open on both ends):
f = nv / 2(L + 0.8d)
[where f is frequency in Hz, n is 1 for one resonance node (for the fundamental frequency), v is the speed of sound in air at 0 deg C (331 m/s), L is the length of the cylinder in meters, and d is the diameter of the cylinder in meters]
The pipe is just a piece of PVC and the mesh is a stack of about 15 2x2 inch squares of 1/4 inch chicken wire.
Unfortunately, due to the use of a blowtorch, the video is not quite as interactive as the previous one. Also, the sound produced by the tube is much louder than it appears to be on the video. In any event, we hope you enjoyed it!
For our next project, we may combine this one with one of our favorite simple machines - pulleys!
It's Dad, again. This time we decided to work on a project that was similar to a demonstration we saw put on by a group from the U of M called the Physics Force. It's a demonstration showing how heat can produce a standing wave in a cylinder. This kind of device is commonly referred to as a "hoot tube", but is more formally known as a Rijke tube, after its discoverer/inventor. Click here for a nice description of how it works.
The sound produced by our 5 foot long, 4 inch diameter tube (I mistakenly said it was 5 inches in the video) is about 101 Hz, based on the following approximation for the resonant frequency of an open cylinder (that is, open on both ends):
f = nv / 2(L + 0.8d)
[where f is frequency in Hz, n is 1 for one resonance node (for the fundamental frequency), v is the speed of sound in air at 0 deg C (331 m/s), L is the length of the cylinder in meters, and d is the diameter of the cylinder in meters]
The pipe is just a piece of PVC and the mesh is a stack of about 15 2x2 inch squares of 1/4 inch chicken wire.
Unfortunately, due to the use of a blowtorch, the video is not quite as interactive as the previous one. Also, the sound produced by the tube is much louder than it appears to be on the video. In any event, we hope you enjoyed it!
For our next project, we may combine this one with one of our favorite simple machines - pulleys!
Subscribe to:
Posts (Atom)