[[ball. . . the initial push. . . it is going as fast. . . the way a human goes down.]]
I’m sorry, what was the topic again?
Rich
I think the original post related to the amount of energy your body uses to traverse a flight of steps on this planet. When we need to walk around in a vacuum tube, we’ll let you know.
I see the confusion here, I think, Konrad. The correct answer is: © Boston, MA, in the year 1792.
Here’s the link to the original question and answer: http://www.straightdope.com/mailbag/mdown.html … you might try to read it first?
The question is not the energy amount of the total system, the question is how much energy the human being needs to exert to traverse stairs.
Well, how about that. I just actually read the column in question. Cecil is right, of course, the body will burn more energy going upstairs. However, you can become sorer from walking downstairs. The extra soreness derived from doing the negative or eccentric phase of any motion would make it seem like you had expended more energy, but it isn’t so.
Just to clarify, though, rok – that Cecil is always right is axiomatic. (The word “always” in this context is defined as an item of faith, and ignores the situation of later evidence not known at the time of Cecil’s initial statement…)
The Mailbag items, however, are not written by Cecil, but by his loyal staff, the Straight Dope Science Advisory Board, who are a bright and energetic lot, but not infallible. Just wanted to clarify.
Ok, I think this question is really simple. I don’t see why you’re talking about the “energy of the entire system”. My answer is that it takes a human just as much energy to go down as up stairs. That was the question and that is my answer, I don’t really see much room for confusion.
Now I’m a first year physics student, and this question seems completely, beyond obvious to me. Now, you haven’t actually said what’s wrong with my explanation so I can’t really rebutt your points. I don’t see what air has to do with it anyway, neglecting friction (as I specified) air pressure would not change anything.
Try posting this question on sci.physics if you don’t want to take my word for it.
A) That answer is wildly, ludicrously wrong in physics. I suggest you try another major.
B) The answer is also wildly wrong in biology. A human body is not a friction-free 100%-efficient machine. (Or have you never noticed that you can get tired just standing still?)
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams
Well, I am a fourth year fitness therapy/kinesiology student, and I can assure this IS a simple question. Read all my responses. If you live in a frictionless gravity free environment, then yes, it would take the same amount of energy. But till then, trust me. You should find the kinesiology class there and take it. It about applying physics to the human body and its motion.
John:
First of all I specifically said I was not counting any biological factors so either you haven’t read my post or you’re merely a cretin.
Secondly, it is not sufficient to say “Your answer is ludicrous” to prove a point. But I guess if you can’t actually find anything wrong with my explanation you have to try other ways…
RokSez: Yes, but as I said I wasn’t counting any friction. And like I said in my last post, I don’t see why you are saying my answer only applies when there is no gravity. You haven’t actually said what is wrong with my explanation apart from stating that it is wrong.
Your major might be fine if we were arguing what makes you more sore but the question is pretty simple: What takes more energy? So it is strictly a physics question.
Again I invite you to post the question to sci.physics. And remember the question is not whether it takes more energy to walk up stairs than to throw yourself down the stairs which is obviously what you and Ckdexthavn are talking about. It is about walking up/down.
I still don’t understand your point, Konrad, so I’m not sure what I’m supposed to “disprove.” The question is worded, does it take more energy to walk upstairs or downstairs. We are saying that gravity exerts a force to assist you in going downstairs, whether you are walking or sliding; and that gravitational force opposes you in going upstairs, whether you are walking or sliding.
You seem to be saying that the answer is different for walking than for sliding? That you concede it takes more energy to slide upstairs than to slide downstairs, but you think it is somehow different from walking?
I have asked our unofficial physicist and penguinist to comment on this thread, I’m hoping she will do so soon. I don’t visit other sites, my time is way too limited to playing online.
The original post is being read too literally if you take it to mean how much actual energy is being used as it relates to the universe. The poster is asking if your body uses more energy (read-works harder) to go upstairs or downstairs. It has nothing to do with potential or kinetic energy, but how much work your muscles do to go upstairs or downstairs. If someone just ran a marathon, and came up to you and said “gosh, I’m all out of energy.” they arent saying they have no more potential for motion. They are saying they are fatigued. Like I said, this has nothing to do with physics, it is ridiculous to apply it here.
roksez: What you have just said about my reasoning is exactly what I’m trying to say about yours. It takes as much energy for your muscles to go up or down the stairs. Not the universe or any of that crap but simple muscle power. What you are talking about is the energy of the entire system.
ck: Exactly, sliding is different from walking. When you slide your clothing absorbs the energy that your muscles would normally take up and that’s why it heats up.
Here’s an example: You jump out a window. It doesn’t take any work at all for your muscles. That’s cause at the end of the jump you are moving very quickly and the energy is absorbed by your bones breaking etc etc…
When you walk down the stairs, even if you started at the same heigh as the window, you are not going very fast at the bottom. Why? Because your muscles had to work to slow you down.
So in the case of the jump you did do work but not with your muscles and it was all at the end in the form of friction and breaking. In the case of the slide that same work was absorbed gradually by friction between you and the slide.
Remember, this is like one of those 12 step programs. To see the truth you must first accept you are wrong. You must want to change. In moments of doubt, say to yourself “I think I am right, while Konrad knows he is right.” There is still hope for you!
The fact that I abandon discussion of a topic does not mean that I concede, but only that I am tired of banging my head against a wall.
Hey, did you know that banging your head against the wall uses the same amount of energy as… oh hell, I’m sick of it too. But a great new invention awaits develpment: are you tired of walking upstairs on a stairmaster?? Now you can go downstairs. It’s just as good a workout.
Seriously-I will give you that the total energy expended is the same, but your muscles do MORE work to go upstairs than down. This means they expend more energy. On the way down, you have bones, tendons, etc. also absorbing energy, so your muscles don’t do as much work.
Roksez: So you’re basically agreeing with me? I specifically said not counting any special forces from the human body, ideal human, no friction etc… Yes compression of bones and tendons does absorb some energy which makes it easier to go down. If you want to test just how little energy is absorbed this way try jumping even one inch off the ground and absorbing the impact on your heels with your knees locked… it hurts. And it doesn’t hurt that much to walk normally so normal walking absorbs even less than that.
BTW the reason they don’t have reverse stair masters is that it would give you almost the same workout but with more likelyhood of knee or ankle injuries.
I’m not agreeing or disagreeing with your argument about total energy consumption(as far as energy in E=MCsquared goes). That argument isn’t my bag, baby 
The problem I have is your literal interpretation of the word energy in the original question. This is not a question having anything to do with physics. If the original post wasnt clear to you, well, sorry, but everyone else understood it. The post should have read,
“Does walking downstairs result in a greater oxygen deficit than walking upstairs?” The answer is NO. However, walking downstairs (the eccentric phase of the exercise) CAN produce more soreness than the concentric phase. This is where the original question comes from. If walking upstairs causes a greater O2 depletion, then why doesnt it necessarily cause a greater soreness. I also addressed this earlier. Like I said, don’t take every use of the word energy so literally. If you see an ad for a Powerbar, and it says “get a BOOST of ENERGY”, do you get mad because you think they are advertising a bar that increases the total amount of energy in the universe? God I hope not. I know you are eager to spread the knowledge you gained in the past year, but use it in appropriate forums.
It take s more energy to walk upstairs than down stairs. after all, you can slide down the bannister, and the only energy you would use(or lose) would be Heat caused by friction…anyway… you cant slide back upstairs… never mind…
roksez: I understood the question perfectly. I am talking about the same energy you are, why can’t you accept this? Oxygen depletion is proportional to energy used since that’s where you get your energy from. I keep repeating this but you don’t seem to get it: I’m not talking about total energy in the universe, just the energy your muslces use.
I don’t know what else to say. I just keep repeating that statement and it’s like you’re ignoring me and just saying the same thing over and over. Have you actually reread your own posts? It’s like you suffer a lapse of memory each time I say I’m talking about the same energy you are.
John: Exactly. But when you slide down a bannister you aren’t walking. That’s why you don’t get tired from sliding down a bannister (except from holding yourself up).
To be simplistic:
When I hike to the top of Camelback Mountain, I’m winded, tired, and need a few minutes of rest. After resting, I hike back to the bottom. I’m not nearly as winded or fatigued when I get there.
when moving upstairs, you have to use enough force to carry your mass in 2 directions, forward, which would be the same as walking normally, and upward, against gravity.
as muscles work in pairs, walking upstairs and downstairs use the same muscle groups,
but because your moving against gravity, walking upstairs uses more energy.
a quick annalogy,
you dont have an excercise machine called a stair-decender. they only go up.