Broch Evans http://brochstar.com Booyah! posterous.com Fri, 19 Aug 2011 07:39:53 -0700 Rock Camp USA http://brochstar.com/rock-camp-usa http://brochstar.com/rock-camp-usa I played at Antone's last weekend as a part of Rock Camp USA. It was a
great show: lot's of my friends and family came to see our band, The
Spirit. We played two songs: "Breaking the Law" (Judas Priest) and
"Rockin' in the Free World" (Neil Young, Pearl JKam version.)

Brochstar_01 Brochattack Brochharmony Brochsolo_02
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Mon, 25 Apr 2011 07:20:00 -0700 HCKC Racing http://brochstar.com/hckc-racing http://brochstar.com/hckc-racing

I race at The Hill Country Kart Club in New Braunfels on weekends. I've been racing since I was 5 and really love it.  Best of all, I've got some great friends who I race with.

 

If you'd like to come out and see me, just go to http://www.hckc.org. We race the second and fourth weekend of every month, except December. I hope to see you there.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Wed, 09 Dec 2009 05:36:00 -0800 Yes, My Dad's a Geek http://brochstar.com/yes-my-dads-a-geek-0 http://brochstar.com/yes-my-dads-a-geek-0
My Dad showed me a simple, cool way of connecting technology (like smart phones) and simple devices (like a wrist-watch) with the inner working of nature (which is to say "physics") the other day. He said he got the idea when he noticed that the bubble in a bubble level "moved" when it was laying on the seat as he drove to Home Depot.

Turns out, his Android-based G1 has a sweet bubble level ("Bubble," developed by Ben Zibble: Go here.). I have a wrist-watch. With these two things, my Dad and I started calculating the speed of all sorts of things we were riding in as we went from a rest state (in other words, stopped) to some state of motion. You can see the tools we used in the pictures below.

So, yes, my Dad's a bit a of geek...but stuff this is also really cool. Keep reading below the pictures to see what we did, and how and why it actually works.

Ready. Set. Go.
OK, here's the fun part: This is where we do the actual experiment. Remember, the scientific method involves an idea or hypothesis, a theory or formula, an actual test and validation, and then a prediction with subsequent validation. Let's test our basic idea by doing a simple experiment.

1) In a stationary car (with someone else driving, like Mom!) set the phone so that it's flat (i.e, level, with the bubble in the center).
2) When the driver starts smoothly accelerating (science teachers will recognize the term "smoothly" here) start the sweep hand on the watch.
3) Note the average angle on the bubble level as you accelerate for some pre-set (and safe) time, say 15 seconds.

Now, ask the driver to note the speed of the car at the end of the pre-set time, but to keep quiet about it. Let's say the angle readout averaged 5 degrees, and that we accelerated for 15 seconds. How fast were we going?

Let's Calculate
Our terminal velocity, given constant (smooth) acceleration, is simply "acceleration multiplied by time." We can relate this to gravity, g, since we are using an inertial accelerometer. Here's our formula:

   v = at(sin(r)g) * t

where g = 32.2 fps/s
and r is 'bubble angle' after converting it from degrees to radians

To convert from degrees to radians: r = (Bubble Angle / 180) * pi, which is about 3.14. 

This gives you the following:

V = (sin( 5/180 * 3.14) * 15  = 42.1 feet per second at the end of 15 seconds. Converting to mph, v = 60/88 * 42.1, which is just under 30 mph. The conversion used is based on 60 mph being 88 feet per second, something my Dad learned from his Dad when he was 8.

Got your answer? Ask the driver how fast the car was going. The actual answer, in this case, should be about 30 mph. While it might make your friends wonder, the answer is NOT "minus 30" if they happen to live in the southern hemisphere. Gravity is pretty much the same everywhere on Earth. 

Why Does This Work?
Ben's Bubble application uses the G1's internal accelerometer. Tilting your phone in a gravitational field is the equivalent of accelerating the phone in a car, train, or plane which tells you something about gravity and its effect on the world around you. This relationship is at the root of what Albert Einstein devoted his life's work to.

Here's the deal: The tilt angle displayed on the phone is derived from an internal set of accelerometers. When the G1's Bubble Level is held stationary, for example when you place it flat on a shelf, the only acceleration acting on the level is due to gravity. If the shelf is level, the bubble sits in the middle. As you tilt the level, the accelerometer responds to its changing orientation by sensing the relative force (in this case, direction -- force is a vector) of gravity as it is exerted along the individual x, y, and z axes of the accelerometer. Say what?

Picture three tubes, each containing two springs like what you'd find in a pen and a marble inside, with the marble between the ends of two opposing springs. One tube is mounted vertically (the z direction), and the other two are mounted horizontally, with one oriented right-left (call this "y") and the other forward/backward (call this one "x"). Sitting on the shelf, the right/left and forward/backward marbles are in the middle of their respective tubes between the opposing spring since there is no net force acting to expand or compress one spring or the other. But what about the vertical tube? Because the marble has mass, the bottom spring will be compressed by the marble while top spring is able to stretch out. The force causing the compression/extension is ... gravity! Thus, the accelerometer can detect which way it's is oriented.

Now, if the accelerometer is titled up until until it is vertical, the "front" spring will progressively stretch and the "back" spring will compress in the same way as the up/down springs had been, just as the springs in your seat are compressed as your arms are stretched away from the steering wheel when you accelerate rapidly in a car. In this analogy, you are the marble. Always remember: Sharp marbles wear seat belts.

The same thing happens with G1 Bubble Level if the phone, while still held flat, is accelerated in a forward direction: The "front" accelerometer relaxes while the "back" one compresses. Acceleration is acceleration, whether due to gravity or your foot on a gas pedal. F = ma. ;-) 

Taking This Further
1) Prediction: Next thing would be to create a little table or chart with some angles and times: Predict how fast you'd be going if the readout was 3 degrees for 10 seconds, or 4 degrees for 20 seconds, an then test your predictions. Trust me: If you get much above 6-8 degrees for times approaching 30 seconds you'd better be on the Autobahn, and above 10 degrees you'd best be on runway with flip-out wings. A commercial airliner will produce a bubble deflection of about 13 degrees on takeoff as it accelerates down the runway for 30-35 seconds. Takeoff velocity is in the range of 130mph to 180mph. Please, do not try and see how far you can push the bubble in your family car, so to speak. Do the math first if you're at all wondering about this.

2) Extension:The marble in the analog accelerometer moves backwards when the accelerometer accelerates forwards. The bubble moves forwards. I'll leave it to you to figure out why the bubble in a bubble level moves in the opposite direction of the marble under acceleration, whether in a digital level like Ben's or in an actual bubble and sight glass level like a carpenter might still use. It's a great thought question (or homework assignment) of its own.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Mon, 10 Aug 2009 12:00:00 -0700 Why I like MAKE Magazine http://brochstar.com/why-i-like-make-magazine http://brochstar.com/why-i-like-make-magazine

2009-08-10_15

This is a projection headphone speaker that I built. I got the idea from MAKE Magazine. My Dad extended my subscription to lifetime for this. Thanks, Dad.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sat, 11 Jul 2009 12:00:00 -0700 Shucking Corn http://brochstar.com/shucking-corn http://brochstar.com/shucking-corn

2009-07-16_17

This is me and my friend Alex, at the beach house in Wingaersheek (near Boston). We go there every summer. Alex and I have known each other since before we knew that we knew each other. That's a long time.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 28 Jun 2009 05:49:00 -0700 The sign said "Minors Only." http://brochstar.com/the-sign-said-minors-only http://brochstar.com/the-sign-said-minors-only

2009-06-29_05

This was fun until TSA started running after me, yelling something about "That's not what it means..." Hey, I made my flight.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 21 Jun 2009 12:00:00 -0700 Lodi Gardens, New Delhi http://brochstar.com/lodi-gardens-new-delhi http://brochstar.com/lodi-gardens-new-delhi

2009-06-21_10

We visited India this summer. It was very different but I really enjoyed it. (Delhi was HOT; Leh was really nice.)

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Wed, 25 Feb 2009 12:00:00 -0800 The Ultimate Riding Machine http://brochstar.com/the-ultimate-riding-machine http://brochstar.com/the-ultimate-riding-machine

This is a machine that I built to climb trees. It works by gravity: The rope is tied to the center of the tree, so when I get on it it swings toward the trunk. That pushes the back wheel into the tree so that I can ride up and flip over. I got the idea by reading MAKE Magazine and looking at some of the mechanical machines I saw there. Note: Always wear a helmet, and think before you do stuff like this. Being upside is very dangerous.

Bike-1 Bike-2 Bike-3 Bike-4
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 11 Jan 2009 12:00:00 -0800 Dog Sledding http://brochstar.com/dog-sledding-3 http://brochstar.com/dog-sledding-3

My Mom and Dad took me dog sledding in California. The dogs pulling us had run in the Iditarod (we watched it on VS at home in Austin). It was really cool to do this -- the sleds are faster than you think.

Dogsledding Dogsledding-dogs
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sat, 10 Jan 2009 12:00:00 -0800 You want me to ski down what? http://brochstar.com/you-want-me-to-ski-down-what http://brochstar.com/you-want-me-to-ski-down-what

We went to Heavenly Valley where I got to ski with Jay (a great instructor) and Ripperoo. We had a great time: I really like skiing. I got to go ice skating with my Mom too. She does a lot of great things for me.

Skiing-what Skiing-ok Broch-jay Skiing-ripperoo Brochjenskating
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 03 Aug 2008 12:00:00 -0700 The Chicken Dance http://brochstar.com/the-chicken-dance http://brochstar.com/the-chicken-dance

1226779843970

Texas has a Chicken Dance. This is not it.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Mon, 14 Jul 2008 12:00:00 -0700 Surf's Up! http://brochstar.com/surfs-up-38 http://brochstar.com/surfs-up-38

Brochsurfing

My Dad took me to Surf School at Wingaersheek Beach. This is where we go in the summer -- it's very nice to get away from the Texas heat.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Wed, 10 Oct 2007 12:00:00 -0700 Cub Scouts http://brochstar.com/cub-scouts-7 http://brochstar.com/cub-scouts-7

What I love about Scouts is all of things we get to do. I'm learning how America was built, to use knife and handle a gun safely now, and how to respect nature. All with Scout Spirit.

Broch_classa_1 Den11bst_20080106 1238334457659 1238334436440 1238264439911
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Tue, 20 Feb 2007 12:00:00 -0800 Two Texans http://brochstar.com/two-texans http://brochstar.com/two-texans

Texans

This is my friend Harrison. Harrison lives in Dallas. This picture of us was taken at the Ft. Worth Stock Show and Rodeo.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 12 Jun 2005 12:00:00 -0700 Canadian Grand Prix http://brochstar.com/canadian-grand-prix http://brochstar.com/canadian-grand-prix
Circuit Gilles Villeneuve, Montreal, Canada.. This was a great race. Kimi won for McLaren Mercedes, ending a long streak of bad luck.

Renault Ferrari Redbullracing
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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans Sun, 09 May 2004 12:00:00 -0700 Spanish Grand Prix http://brochstar.com/spanish-grand-prix http://brochstar.com/spanish-grand-prix

We went to Barcelona for the Spanish Grand Prix. It was really cool. I got see to Michael Schumacher racing, too.

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]]> http://files.posterous.com/user_profile_pics/197533/Skyhawks.gif http://posterous.com/users/4bmXldvqdVlf Broch Evans brochstar Broch Evans