What would use more energy?

[Guest]

I'm not exactly sure how to phrase this question, but ..

What would use more energy, standing holding a book weighing W pounds in one hand and letting the other hand hang by your side, or using both hands to carry the book?

-Who

 

[Michael Redman]

I say both hands, because you're holding a second arm up. If you were a solid object, it wouldn't matter, but because it takes energy to hold your arms in an elevated position, in addition to the energy you're expending simply bearing the weight of your arms as body mass, the two hand method uses more energy.

 

[Crossbow]

Hold the object straight out.

Not to sound pedantic, but there are two definitions of energy which I think are appropriate here and both argue the same point but in different ways.

First, using energy to describe physical vigor and strength. It will take more energy to hold the book straight out from you as opposed to holding the book to your side.

Second, using the physics definition which is that energy is the ability to do work. So if the book is held straight out from your body, it will be a bit further from the surface on which you are standing that if it were held at your side. Therefore, the book will have more potential energy if it is held straight out instead down low.

I hope this helps!

 

[Soapy Sam]

This varies, depending on the magnitude of W.
eg. If W is 150lbs (heavy reading), and you hold it in one hand, you will fall over, which requires no energy at all.

 

[Patricio Elicer]

I think that it's again a matter of "efficiency". The energy "spent" in doing a certain "work", depends on how efficient the means to do it is. In less efficient means, more energy is lost in the form of heat.

In this sense, I think that using both hands is more efficient than using a single one, since less energy is lost. The amount of sweating is a measure of how efficient a method is, and in fact we sweat more using one hand than using both (given that the object is heavy enough to realize this fact)

 

[Guest]

Thanks for the responses. I was wondering, mainly, because holding a book with one hand is more difficult than holding it with two hands, but when I use two hands, both arms are tensed instead of one arm (although, individually these two arms are tensed less than that one arm when only one hand is carrying a book).

And, if it matters, by carrying a book I mean something like this

---B---

where the -'s represent the palm of your hand, and B the book, let's say 5lbs, and you are holding the book much like a waiter would hold a tray of food.

-Who

 

[Soapy Sam]

Whodini-
It was the same restless sense of scientific curiosity that led to Dr. Elmer Naugahyde's discovery of the reclining armchair, previously known only in it's native environment of stuffy Bavarian University Clubs. If that was not a breakthrough, then what was? The great days of science are not all behind us.

Seriously, I often find threads about apparently simple questions are the most interesting and productive we have- I often find I have been subtly misunderstanding a concept for years . Also we tend not to get into name calling- which is refreshing.

 

[BillyJoe]

Whodini,

First of all, you don't use energy, you transform it.

Ignoring the weight of the arms holding the book (Michael Redman, you idiot ), there should be no difference in the amount of energy transformed.

But Don't worry Michael, Crossbow (the fool ) has completely misread the question and so he has absolutely no hope of answering it

But Patricio got it right so I'll just ignore him and press on.

The problem is that the efficiency of muscle action is not a horizontal straight line graph but a line curving upwards to the right. The heavier the weight, the less efficient the muscle action. W divided between two groups of muscles equals W/2 for each muscle group. Two muscle groups lifting W/2 each is more efficent than one muscle group lifting W.

And poor old Delusional ( ) Sam might like to explain how he got all those bruises without any energy being transformed???

regards,
BillyJoe.
(What? Name calling? Who? )

 

[Soapy Sam]

I'm not delusional. I'm deluded. Dere's a difference.
By the way, does anyone know how to get Cheddar into a syringe?

 

[BillyJoe]

I'm not delusional. I'm deluded. Dere's a difference.

Dictionary.com

de·lu·sion ( P ) Pronunciation Key (d-lzhn)
n.

The act or process of deluding.
The state of being deluded.

 

[aggle_rithm]

I'm not exactly sure how to phrase this question, but ..

What would use more energy, standing holding a book weighing W pounds in one hand and letting the other hand hang by your side, or using both hands to carry the book?

-Who

Ask Uri Geller. He uses both hands to paranormally bend a spoon.