Power
lborkowski | January 7, 2016by Jonathan Heller
Most public health practitioners, and those who work on health impact assessment specifically, want to improve the health of vulnerable populations. Most efforts to do so are well-intentioned, yet they often don’t lead to significant change. What do we need to do differently? Below is an analysis we at Human Impact Partners put forward.
What Do We Mean By Inequity and What Are Its Causes?
First, we are intentional in our choice of the word equity. Health inequities, as Margaret Whitehead said, are differences in health status and mortality rates across population groups…
esiegel | November 24, 2013"Education is a continual process, it's like a bicycle... If you don't pedal you don't go forward." -George Weah
I don't know how many of you out there have an office day job, sitting hunched over at a desk for the better part of 8+ hours a day, but it's pretty well known that it's not only bad for you, but it feels bad to do, physically. Staying in one motionless position or posture for too long is the culprit, and Leo Kottke's music might make you want to get up and move if you have a listen to his song,
Busted Bicycle.
And while there are options out there for those of you with autonomy…
rallain | July 30, 2010The Lord of the Rings trilogy came on TV again recently. My wife and I can't help but to watch this even though we have it on DVD. Anyway, I was thinking about the part where Gondor sends a signal to Rohan asking them for military aid. Since this was before the invention of email, they had to do it with a signal fire. Hopefully this clip won't be a spoiler for you, but this is from the movie. Actually, all of the clips available have embedding disabled. So this is just a picture of that clip. If you want to see it, go to the youtube version.
One other spoiler: Sauron is really Frodo's…
rallain | July 23, 2010Check this out - NY Times: No Motors, but Mistrust at Tour de France.
So, the short story is that some people claim that Cancellara is cheating by putting a hidden electric motor in his bike. Now they are going to do random hidden-motor checks.
I have analyzed this motor-in-a-bike already:
Energy in a hidden battery: The short answer is that you could get about 500 watts for about 1.5 hours with a hidden battery that weighs 1.6 kg. Doable, yes. Advisable? Probably not. Also, you would probably hear the motor being used.
Do bikers cheat? In this post I look at some clips of Cancellara…
rallain | May 31, 2010We went to the aquarium, the kids like it. In the Amazon river section, they have an electric eel. Here is the sign next to the Eel.
Sorry for the poor image quality. I took the picture with my crappy phone and didn't even realize it was bad until later. I used some magic on it to make parts of it readable, but if that was not good enough, here is what it says:
The Electric Eel is the most powerful of all the electric fishes. It can discharge up to 650 volts: six times the power of a household current. A shock can fend off attackers or stun prey so the eel doesn't risk getting hurt in…
rallain | May 3, 2010This video seems like it is getting popular, but maybe that is because it is so awesome.
Maybe it is just me, but I find this video very visually satisfying. I love the way they compare the different runners.
Anyway, there is some physics here. Commenter Ben sent me the link to this video (thanks!) with some great questions. Which of the runners has a greater kinetic energy? What about the power? These aren't too difficult to answer, but the first thing is to get the data. There are several options (including just using a stop watch). But no, that is not good enough for me. Instead, I…
rallain | March 23, 2010I already looked at ESPN's Sport Science episode where they calculate that Marshawn Lynch produces 54,000 watts when pulling some tires. Yes, that is way too high. However, what would happen if some was actually that powerful? What could that person do? How fast could they run 100 meters? That is what I am going to calculate.
First, I am going to assume that Marshawn has a mass of about 100 kg. Also, let me say that he can produce 54,000 watts no matter what his speed.
Take a short time interval. During this time, Marshawn will increase his speed from say v1 to v2 this would be a…
rallain | March 19, 2010Let me be clear. I am not really an attacker. If someone wrote a report about ski jumping or something and misused the word "momentum", no big deal. However, if you have a show that claims to be about SCIENCE and you are obviously putting a lot of money into this show AND a whole bunch of people will see and think this is science - then you need to be a little careful. I think shows like ESPN's Sport Science are a good idea - you know, introduce some cool science ideas by using cool sports. This show just needs some help.
Yes, I know I make mistakes. I try to correct them when I become…
rallain | February 28, 2010I ride my bike and mostly the wind makes me unhappy. On a very few days the wind is with me on the way to work and then changes so that it is with me again. But most days the wind is fairly constant. So, if the wind is constant then shouldn't everything even out? (Even Stephen).
Assumptions:
Let me start with the assumption that I (a mere mortal) can output at a constant power (but not 57,000 Watts like some people). I will also assume an air resistance force that is proportional to the square of the relative air speed. Here is a diagram.
A couple of quick things to point out. First,…
rallain | February 9, 2010Forgive me for all the posts on ESPN's Sport Science (example: Pulling and Power). I can't help myself.
In the short episode recently, Sport Science compared a football player pulling a sled with huge tires on it to a truck pulling stuff. I think their goal was to compare the power per kg from for the player and the truck to show how awesome humans are (and let me just say that humans ARE awesome). The problem was that they really didn't give the truck a fair chance.
For the first test, they had Marshawn Lynch pull 585 pounds of stuff. The real question should be: how hard does he have to…
rallain | February 9, 2010Note: This is part of my ongoing attack of ESPN's show Sport Science. Really, I am continuing to look at the episode where they calculate a football player can produce 57,000 Watts by pulling some stuff. Wait...I don't want to limit my stuff to Sport Science. I see this stuff all the time. The problem is that people confuse the force needed to move something with its weight.
So, you want me to pull something? Great, I am a physics guy. I could probably pull maybe 100 pounds. That seems reasonable? But wait! I will increase it to 500 pounds! That is like two huge football players.…
rallain | February 7, 2010I would like to continue my attack on the show Sport Science - ESPN. In this short episode, they are comparing the power of NFL player Marshawn Lynch with that of a truck. You can watch it here if you would like.
There are two things that are not quite right with this episode, first, the power thing. I will save the friction problem for another post. So, if you didn't watch that clip, the basic idea is that Marshawn pulls some heavy tires. Sport Science then calculates the power needed to do this and then repeats a similar thing for a truck. Quick review. What is power? In short,…
rallain | February 2, 2010This one has been on my mind for quite some time. What kind of power source would you need to run a lightsaber? I was actually worried recently about this post when I saw the Discovery Channel show "Sci Fi Science". In that particular episode Michio Kaku talks about how you would actually build a lightsaber. The episode was a little silly, but the science wasn't too bad. In end Michio decides to build a type of hand held plasma torch. Doing this, he estimated that the lightsaber would need a power source on the order of mega-watts.
He didn't do what I was thinking. I am thinking about…
stoat | January 22, 2010Isn't this beautiful:
Story behind it from withouthotair.blogspot.com/2010/01/wind-farm-wakes.
rallain | June 23, 2009This was on my 'to do' list, but Tom at Swans on Tea beat me to it. Basically, this grocery store has these plates that when depressed produce electrical energy. Tom does a good job pointing out that this is not free energy (the original article says this also). Clearly, the energy comes from the cars. How much would this cost the cars?
As always, let me start with some assumptions.
The original article says that the bumps will generate 30 kW of energy every hour. That is an odd thing to say. I am going to interpret that as 30 kW of power for all hours (every hour). They couldn't have…
rallain | May 18, 2009Another electric motorcycle post. (Here is the post on the wind-recharged drag racing motorcycle) This new one is a solar powered motorcycle. The site claims that the bike can go 50 miles on a full charge (from Gas2.org). This is easily possible, but how long would it take to charge with normal solar panels? Here is an image of the bike.
Questions to be answered: How much energy would the bike need to go 50 miles? How much power (average) could you expect to get from the solar panels? And...how long would it take to charge this sucker. I am sure you can store enough energy in a…
rallain | May 5, 2009I just realized that something has been bothering me. It is this KillaCycle - the electric zoom-fast motorcycle that I posted about previously. It clearly is super fast. However there are two claims that seem iffy.
It can be recharged in 4 minutes.
It is recharged by wind power.
It may be possible that these individually could be true - but could it be recharged in 4 minutes by the wind? I am not sure. Let me do some estimations to see if this is possible. What am I starting with:
From the review on gas2.org, uses cordless drill batteries.
Uses 1200 batteries
Produces 500 bhp - not…
rallain | April 21, 2009First: Car Talk is awesome. I wish I could come up with some class activities that help students become as good at trouble shooting and critical thinking as Tom and Ray are. Anyway, they are quite entertaining.
So, my Dad called and told me he heard a discussion on Car Talk about the effect DC to AC converters and accessories plugged in to it and how they would effect gas mileage. I skimmed through the last Car Talk podcast, but couldn't find it. He must have heard a re-run on the radio or something (he doesn't really believe in podcasts). Let me calculate the effect a number of things…
bioephemera | April 16, 2009You've never heard "in real time" screamed with so much passion. Not just one, but two big-haired metal-band bio-rock videos after the fold. . .
(sources: here and here)
rallain | April 11, 2009It is spring break, so we are at my parents house for a couple of days. The kids like it because there is a pool, a heated pool even. It really isn't that cold outside, but yesterday the water measured at 62 oF. So, with some help from the kids, we cleaned out the pool and turned on the heater. We also put a cover on it, hopefully to help it heat up some more.
This is perfect for a quick calculation. Is it reasonable that the pool could get up to a swimable temperature by tomorrow? Let me first make some assumptions and data:
15,000 gallons of water in the pool. This is about 57 m3.…