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Impulse/force in pounds for the time frame

by waynexk8
Tags: frame, impulse or force, pounds, time
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sophiecentaur
#91
Jan29-12, 10:28 AM
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Calculate the peak force needed to throw a computer out of a window in sheer exasperation!
waynexk8
#92
Jan29-12, 04:16 PM
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Quote Quote by sophiecentaur View Post
Can't ba answered if you don't know the acceleration, I'm afraid.
Will change to Metric.

Hmm, thought I had put enough information in, as if I am moving the weight 500mm at every .5 of a second, I decelerate for say the last 20% thought you would/could work this out, or am I doing it wrong ??? Seems I was wrong interesting.

I am moving the weight on 1, at 1m/s. {m/s 1 meter per second}

I am moving the weight on 2, {which is now 83mm} in .5 of a second. Moving it at 83m/s. {83mm per second} This is basically going at a constant speed, as its accelerated to moving at 83m/s.

So are you saying that I could have different accelerations and decelerations ??? This is as I thought, but D. {douglis} seems to think other. {that is right is it not D. ???}


Quote Quote by sophiecentaur View Post
Force=Mass X Acceleration
(Then add the weight, in this case)
Misunderstand that a little, so best say and ask.

Quote Quote by sophiecentaur View Post
Are you assuming constant force all the time?
Hmm, with a muscle it would not be a constant force, but let’s says it’s a machine moving the weights and the force is constant.

Wayne
waynexk8
#93
Jan29-12, 04:39 PM
P: 399
Quote Quote by douglis View Post
Again that question.Define the value of force you're interested in.The peak...the average or the "total" force(integration of force in respect of time)?
Impulse force, total, overall, integration of force in respect of time.

Quote Quote by douglis View Post
For the peak force...we need more data.
Enough now for 1 and 3, as 2 will not be much higher than the weight.

Quote Quote by douglis View Post
For the average force....in both cases you start and end at rest.The net change in momentum is therefore zero,
How do you work out the net change in momentum/movement is zero ??? As the net force in 1 = 500mm and in 2 = 166mm. So the net, total momentum/movement will be 500 and 83 ???

I start at rest and end in rest, but the distance move on 1 = 500mm and 2 = 83mm

Quote Quote by douglis View Post
which is equal to the net impulse delivered. Therefore, the average force is equal with the weight in both cases....80 pounds or 356N.

For the "total" force....again in both cases is equal with gravity's impulse for .5sec.So...356 X .5=153N*s.
See, I don’t get how you come to this, as the below, shows the total or overall force to be higher for the faster moving in less time ??? And its not the peak. Please see the video stating that more overall, total force was used with the fast rep, but this time the more force was used in "less" time, go from 5 min.

http://www.youtube.com/watch?v=6clCe76uD-Q

Fast
P = 695
F = 579Newtons
V = 192

Slow
P = 649
F = 546Newtons
V = 161

Wayne
waynexk8
#94
Jan29-12, 04:51 PM
P: 399
Quote Quote by sophiecentaur View Post
Calculate the peak force needed to throw a computer out of a window in sheer exasperation!
WaynesWorldphysics ???

Please sophiecentaur, could you work out what the Newont force is below is, peak, average or total ???

Go from 5 min.

http://www.youtube.com/watch?v=6clCe76uD-Q

Fast
P = 695
F = 579Newtons
V = 192

Slow
P = 649
F = 546Newtons
V = 161

This one may help.

http://www.youtube.com/watch?v=Ycu6y...eature=related

Wayne
waynexk8
#95
Jan29-12, 04:55 PM
P: 399
Quote Quote by sophiecentaur View Post
So that is your definition of 'Integration'? It is not the Mathematical definition that is used (and works) in Physics so there is no point in your using the term.
I will write to an EMG expert, and ask then on intergration and RMS.

I will also write to the makers of my machine, and ask them what actualy my machine reads out on the average.

Wayne
waynexk8
#96
Jan29-12, 05:13 PM
P: 399
D. I just thought of somthing, I can video the machine and prove its NOT the peak force, but the average. Or you should be able to work it out here.

Take a look at the slow rep video, you will notice the peak force = ??? was it a 190 somthing ??? BUT the average was a 140 !!!

http://www.youtube.com/user/wayneroc...36/B8gtpp8ozvU

What do you say to that my friend D. ???

Wayne
waynexk8
#97
Jan29-12, 05:21 PM
P: 399
Quote Quote by sophiecentaur View Post
How can the machine distinguish between situations where there are and there aren't antagonistic muscles at work?
If I am curling, arm flexion, then I will but the four pads on my biceps, as these are the prime moves.

Quote Quote by sophiecentaur View Post
Are you saying that your machine 'knows' when your arm is moving and when it's stationary? Does it know then you are holding, lifting and lowering the weights?
Yes the machine know when my arm is moving and when it's stationary, holding, lifting and lowering the weights. As the pads detect “all/every” of the electrical signals in my muscles the pads are on.

Here take a look at the makers video, go to 1.40min

http://www.youtube.com/watch?v=hG3EgCF90_I

Or I could make a video if you want.

So if they say the fast as a higher average, as a Physicist, thought you would be very interested, that is, if you do agree with D ??? But to me he has not added in all the variables, like ground reaction muscle force and so forth, and left out Kinology and Biomechanics.

Quote Quote by sophiecentaur View Post
How can you expect to get a proper answer whilst you still insist on using the term force/strength? Do me a favour and look the individual words up. They describe entirely different aspects of Physics. Which one do you mean when you use that term? Why do you hang on to these deliberately nonsense terms instead of using the right one? You are saying black is white on every occasion.
Ok sorry, I will try the stick with force.

Quote Quote by sophiecentaur View Post
The very least you could do, if you really do want some sense, is to use the correct terms. Imagine you had a calculator and the + key sometimes gave you a - and the X key sometimes gave you a ÷. You would say it was rubbish, wouldn't you? Constantly using confusing terms is the equivalent to a dodgy calculator.
Ok get your point.

Quote Quote by sophiecentaur View Post
At least, you could do us all the courtesy of talking the right language. (The language that 11 year old kids are quite happy to learn to use in School.) Don't ask me to help you with this - just look up any word you want to use and see if it actually fits what you want to say. I get the impression that you are not looking anywhere else for your information but just want to be spoon fed by PF. This is unreasonable.

btw, I don't have to justify the Physics Equations in this context. They work fine for everyone but you so I am not out of step here. Give me a proper question (not ten pages of weight lifting jargon) and I can guarantee a good answer. Give me another 'Wayne' question and there will be no available answer from Physics.
Ok, I will try and use physics, if I cant will ask.

Wayne
sophiecentaur
#98
Jan29-12, 06:16 PM
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Quote Quote by waynexk8 View Post
WaynesWorldphysics ???

Please sophiecentaur, could you work out what the Newont force is below is, peak, average or total ???
1. If you can't tell me the acceleration (i.e. what is the variation of velocity with time during the lift? There are infinite possible combinations that will get the weight from bottom to top of the lift in a given time.) I cannot tell you the force. (Did you not read my F=mA formula?)

2. Because the weight starts and ends stationary, the Mean additional force must be zero and the mean force will be the weight.. (I think this had been pointed out several times already.)

3. What does "total force" mean? Do we add up the forces, measured every second, every tenth of a second, every 100th of a second???? It's a nonsense concept as you can only validly add forces that operate at the same time.. Ask the makers of your machine for an answer. There is not a PF answer for you.

It matters not whether you are working in Imperial or Metric - all three questions are either nonsense of indeterminable.
waynexk8
#99
Jan30-12, 07:00 PM
P: 399
Big thank you for staying with me.

Quote Quote by sophiecentaur View Post
1. If you can't tell me the acceleration (i.e. what is the variation of velocity with time during the lift? There are infinite possible combinations that will get the weight from bottom to top of the lift in a given time.) I cannot tell you the force. (Did you not read my F=mA formula?)
Hmm, I thought I told you this on my other post ??? Ok, this is where your help will have to come in, as I am not sure how to work this out. Can we call it for now a constant acceleration ??? If so, on 1, the weight accelerates from rest to 400mm in 0.4 of a second, then decelerates the last 100mm in .1 of a second

Quote Quote by sophiecentaur View Post
2. Because the weight starts and ends stationary, the Mean additional force must be zero and the mean force will be the weight.. (I think this had been pointed out several times already.)
So as I push up with the force of the weight to move the weight, and then the weight cancels that force out, then you call the mean additional force {that my muscles creating force} must be zero ??? If I am right, sort of get that, however, I have used forces, from a 100 to 1 pounds, and that’s all we are concerned about ??? Or am I missing something.

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.

Not sure you get what I say there, please say if you don’t, it’s like a person hits you with great force, and it hits you down, but it would take far more lower force hits and more “time” {but in this debate the time is the same} to hit you down with lower force hits. THIS is why you always fail at lifting the weight, or you hit momentary muscular failure faster with the faster reps, as they ARE doing more damage with the higher forces.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the ENG states more average force used in the faster reps.

Quote Quote by sophiecentaur View Post
3. What does "total force" mean? Do we add up the forces, measured every second, every tenth of a second, every 100th of a second???? It's a nonsense concept as you can only validly add forces that operate at the same time.. Ask the makers of your machine for an answer. There is not a PF answer for you.

It matters not whether you are working in Imperial or Metric - all three questions are either nonsense of indeterminable.
What I mean with total or overall force, is that if you lift say 80% of your 1RM, you can only lift it for a certain amount of times in a time frame at a certain speed. Let’s say you could lift it up and down 10 times at 1 second up and 1 second down, then at 20 seconds you could not lift it again, so you had in your muscles 20 seconds or 10 lifts in you at that rep speed, of force, after that your force was temporary no longer. Yes I know that sounds a bit daft, but that is actually what happens, and if you had lifted the same weight up and down in .5 of a second up and .5 of a second up, you would have most probably failed to lift the weight in 10 to 12 seconds. Meaning you have used up your temporary force up far faster.

So let’s “just” {please this is just an example to get my point over} say for an example you had 1000 forces to lift the weight, in the fast, you used up this force far far far faster, meaning if you both lift the weight for a set time, and do “not” lift until momentary muscular failure, the faster reps “must” be using up more force faster, as you fail faster lifting faster. Example of how the fast are using more force and faster, more energy used, more distance the weight has been moved, faster to muscular failure, the EMG states more muscle activity or muscle force. I know all the above sounds a bit complicated, but there is total since in there.

Thank you again for you time and help, not sure about the acceleration, hope to learn more on that.

Wayne
douglis
#100
Jan31-12, 01:38 AM
P: 148
Quote Quote by waynexk8 View Post
Big thank you for staying with me.

Hmm, I thought I told you this on my other post ??? Ok, this is where your help will have to come in, as I am not sure how to work this out. Can we call it for now a constant acceleration ??? If so, on 1, the weight accelerates from rest to 400mm in 0.4 of a second, then decelerates the last 100mm in .1 of a second
O.K. I'll try to help you understand once again.
Let's say in your above example the load is 800N(81.5kg) while your maximum force ability is 1000N.

For the first 0.4sec you're applying your Fmax (although in reality that's biomechanically impossible) so the net force is 1000-800=200N.
So your acceleration for those 0.4sec is a=F/m=200/81.5=2.45m/s^2

For the last 0.1sec you let the gravity decelerate the load so the net force is -800N
So your acceleration for those 0.1sec is a=F/m=-800/81.5=-9.81m/s^2 and obviously it's equal with g.

So as I push up with the force of the weight to move the weight, and then the weight cancels that force out, then you call the mean additional force {that my muscles creating force} must be zero ??? If I am right, sort of get that, however, I have used forces, from a 100 to 1 pounds, and that’s all we are concerned about ??? Or am I missing something.

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.
As I proved you above you used positive acceleration equal with 2.45m/s^2 for the 80% and 4 times greater negative acceleration equal with -9.81m/s^2 for the last 20%.
That's why we're telling you the acceleration is offset by the deceleration.The average acceleration is always zero.
In the equation of force F=mg+ma the "ma" part is always zero so F=mg or else the force is equal with the weight.No Mean additonal force is required.The forces "make up","balance out" or call it whatever you like.

I don't believe it's possible to get a more simple explanation.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the EMG states more average force used in the faster reps.
No...your EMG states that greater RMS is used in faster reps...not average force.

What I mean with total or overall force, is that if you lift say 80% of your 1RM, you can only lift it for a certain amount of times in a time frame at a certain speed. Let’s say you could lift it up and down 10 times at 1 second up and 1 second down, then at 20 seconds you could not lift it again, so you had in your muscles 20 seconds or 10 lifts in you at that rep speed, of force, after that your force was temporary no longer. Yes I know that sounds a bit daft, but that is actually what happens, and if you had lifted the same weight up and down in .5 of a second up and .5 of a second up, you would have most probably failed to lift the weight in 10 to 12 seconds. Meaning you have used up your temporary force up far faster.

Wayne
This is the last time I bother to even read that particular question.

You "fail" in a weight lifting set when you have no longer enough energy to apply force equal with the weight.
"Failing" faster with a certain kind of lifting means that with this kind of lifting you spend energy at a higher rate....NOT that you use more force.In all cases the average force is equal with the weight.
It's the fluctuations of force that are more energy demanding.That's the only scientific answer you can get.
waynexk8
#101
Feb1-12, 04:50 PM
P: 399
sophiecentaur I see you’re an Engineer, so hopefully you will be able to understand what I am saying, even thou a lot is not in pure physics talk, please, and I am not being sarcastic, as I know people find it hard the way I explain things, but please do you understand what I am trying to say in the below please ???

And please, if you agree with me or not, {AND YOU D.} do you understand what I am trying to say convey too you ??? As this is very important, as it makes no difference if you agree or not now, only that you both and other members actually understand what I am “trying” to say ???

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.

Not sure you get what I say there, please say if you don’t, it’s like a person hits you with great force, and it hits you down, but it would take far more lower force hits and more “time” {but in this debate the time is the same} to hit you down with lower force hits. THIS is why you always fail at lifting the weight, or you hit momentary muscular failure faster with the faster reps, as they ARE doing more damage with the higher forces.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the EMG states more average force used in the faster reps.


Big thank you for staying with me.
Originally Posted by sophiecentaur
1. If you can't tell me the acceleration (i.e. what is the variation of velocity with time during the lift? There are infinite possible combinations that will get the weight from bottom to top of the lift in a given time.) I cannot tell you the force. (Did you not read my F=mA formula?)
Hmm, I thought I told you this on my other post ??? Ok, this is where your help will have to come in, as I am not sure how to work this out. Can we call it for now a constant acceleration ??? If so, on 1, the weight accelerates from rest to 400mm in 0.4 of a second, then decelerates the last 100mm in .1 of a second

Originally Posted by sophiecentaur
2. Because the weight starts and ends stationary, the Mean additional force must be zero and the mean force will be the weight.. (I think this had been pointed out several times already.)
So as I push up with the force of the weight to move the weight, and then the weight cancels that force out, then you call the mean additional force {that my muscles creating force} must be zero ??? If I am right, sort of get that, however, I have used forces, from a 100 to 1 pounds, and that’s all we are concerned about ??? Or am I missing something.

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.

Not sure you get what I say there, please say if you don’t, it’s like a person hits you with great force, and it hits you down, but it would take far more lower force hits and more “time” {but in this debate the time is the same} to hit you down with lower force hits. THIS is why you always fail at lifting the weight, or you hit momentary muscular failure faster with the faster reps, as they ARE doing more damage with the higher forces.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the EMG states more average force used in the faster reps.

Originally Posted by sophiecentaur
3. What does "total force" mean? Do we add up the forces, measured every second, every tenth of a second, every 100th of a second???? It's a nonsense concept as you can only validly add forces that operate at the same time.. Ask the makers of your machine for an answer. There is not a PF answer for you.

It matters not whether you are working in Imperial or Metric - all three questions are either nonsense of indeterminable.
What I mean with total or overall force, is that if you lift say 80% of your 1RM, you can only lift it for a certain amount of times in a time frame at a certain speed. Let’s say you could lift it up and down 10 times at 1 second up and 1 second down, then at 20 seconds you could not lift it again, so you had in your muscles 20 seconds or 10 lifts in you at that rep speed, of force, after that your force was temporary no longer. Yes I know that sounds a bit daft, but that is actually what happens, and if you had lifted the same weight up and down in .5 of a second up and .5 of a second up, you would have most probably failed to lift the weight in 10 to 12 seconds. Meaning you have used up your temporary force up far faster.

So let’s “just” {please this is just an example to get my point over} say for an example you had 1000 forces to lift the weight, in the fast, you used up this force far far far faster, meaning if you both lift the weight for a set time, and do “not” lift until momentary muscular failure, the faster reps “must” be using up more force faster, as you fail faster lifting faster. Example of how the fast are using more force and faster, more energy used, more distance the weight has been moved, faster to muscular failure, the EMG states more muscle activity or muscle force. I know all the above sounds a bit complicated, but there is total since in there.

Thank you again for you time and help, not sure about the acceleration, hope to learn more on that.


Wayne
sophiecentaur
#102
Feb1-12, 05:17 PM
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Wayne
You still don't get it, do you?
Whatever you 'feel' in your arms and whatever you think that machine is telling you, my points 1,2 and 3 still apply.

1. You can't say it's accelerating constantly all the time. If it were, then it would still be moving at the top. It isn't because, of course, it stops at the top. And, in practical terms, you have no way of knowing without measuring the velocity at very short intervals over the whole of a lift.

2. For the weight to start at zero velocity and to end at zero velocity then the average force Has to be weight. This may annoy or confuse you and it may not be what you think the machine is telling you but is true beyond any shadow of a doubt. You could ask Sir Isaac Newton himself and he would tell you the same.

3. You actually don't know what you mean when you talk of "total force" because you are after an arm waving description of what it feels like to do a lift. I really don't know why you won't accept (from not just me but others, too) that your idea can't be stated in Physics.

What you could find out (but only by measurement) would be the maximum force, the total work done on the weights (thats N lifts times weight times height) and the Power developed (dividing the total work done by the time for the whole exercise).

I don't understand why that isn't enough.
All the other acres and acres of figures you have written on these pages have been pretty much wasted. I'd bet that no one has actually read more than a few sample lines of it and then given up.

How can you be so sure that your question is reasonable when, in the same breath, you admit to not knowing much real Physics?

I have seen some of the movies on your website and I am really impressed by your dedication to your sport. You are clearly a bit of an expert on the practical aspects of it and your advice on how to do the exercises and how to body build is, no doubt, correct. But, when it comes to the Physics of the situation, you just have to be much more rigorous and 'go along with the rules'. Those rules say that you are on a fruitless quest and have been talking mostly rubbish. Why are you bothering and why can't you just accept what you are being told? Do you just like a friendly chat - is that what it's all about?

That is a DEAD PARROT!
waynexk8
#103
Feb1-12, 06:13 PM
P: 399
Quote Quote by douglis View Post
O.K. I'll try to help you understand once again.
Ok thx.

Quote Quote by douglis View Post
Let's say in your above example the load is 800N(81.5kg) while your maximum force ability is 1000N.
Right.


Quote Quote by douglis View Post
For the first 0.4sec you're applying your Fmax
Right.

Quote Quote by douglis View Post
(although in reality that's biomechanically impossible)
Right.

Quote Quote by douglis View Post
so the net force is 1000-800=200N.
This is where you sort of lose me. As you saying ??? The net force on me and the weight = 200N ??? If so I am still with you, but why say the net force on my muscles and the weight ??? AND WHY take 800 from 1000 ??? As we are only concerned with the weight/force on me, my muscles.

So am I not right in saying what physics states, is the net force on me, my muscles is only the weight = 800N ??? But that’s “only” when you are holding the weight of moving it very slow.

Now here’s where it get a little more complicated. As if you agree that there is 800N pushing down and me pushing up with 800N, the moment I try too accelerate it as fast as possible I will be pushing up with a 1000N, but not only that, but the weight of 800N will not only be pushing back down with just the 800N, but as of the acceleration components, the weight will pushing down more than 800N as of the action reaction law ???

So you you weight me and the weight on the scales, it could register ??? 400 pounds, but the faster I try to accelerate, the more weight/force is pushing back onto my muscles as the reading on the scales goes up and up the faster I try to accelerate.

Quote Quote by douglis View Post
So your acceleration for those 0.4sec is a=F/m=200/81.5=2.45m/s^2
Right.

Quote Quote by douglis View Post
For the last 0.1sec you let the gravity decelerate the load so the net force is -800N
Not sure on you here, are you saying that only gravity does the work and force on the weight for the last 0.1 of a second ??? If so I do not agree there, as I have to keep pushing for the weight to keep moving. I decelerate the weight, if the weight was heavier or lighter, or if gravity had more force or less force, I my muscles decelerate the weight, I am in full control, especially on 80% if we were talking of 20%, then the accelerating components will be helping moving the weight after a certain speed/force is applied to the weight, as if I immediately stopped, the weight would keep moving.

Quote Quote by douglis View Post
So your acceleration for those 0.1sec is a=F/m=-800/81.5=-9.81m/s^2 and obviously it's equal with g.
Sorry you lose me a little there ??? Equal with g ??? I know what g is, but not sure why you are saying equal with it.

Quote Quote by douglis View Post
As I proved you above you used positive acceleration equal with 2.45m/s^2 for the 80% and 4 times greater negative acceleration equal with -9.81m/s^2 for the last 20%.
That's why we're telling you the acceleration is offset by the deceleration.The average acceleration is always zero.
Right get what you’re saying here, and have done all along, your sort of saying, and I know this is different, but want you to understand that I understand. You’re saying that when my accelerations are higher than your forces, that your forces make up or balance out when my forces are on the decelerations ??? [b]BUT what I am saying, is that it may look that way on paper, but how do you think your 80 medium force, can make up for/to my 100 force ??? I am saying to do this; you would need FAR more time using your 80 force for the tension to build up on the muscles.

As “IF” you did make up or balance this force up, thus make up or balance this opposite action reaction tension on the muscles, HOW and WHY do I use “more” overall/total energy ??? How/why do I move the weight “more” overall/total distance ??? How and why do I fail roughly 50% faster “more” ??? How and why does the EMG read out far more muscle activity, force on the faster rep.

Four definite things prove you “CAN’T” be making up the force, see my point ???

Don’t you get, that your measure or force does and can never equally my higher force !!! Thus you have to need more time to let your force put more tension on the muscles. A small force applied for a LONGER TIME produce the same momentum change as a large force applied briefly, because it is the product of the force and the time for which it is applied that is important.

Quote Quote by douglis View Post
In the equation of force F=mg+ma the "ma"
You lost me on ma, I need to know what that is for me to understand you point.

part is always zero so F=mg or else the force is equal with the weight.No Mean additonal force is required.The forces "make up","balance out" or call it whatever you like.

I don't believe it's possible to get a more simple explanation.



Quote Quote by douglis View Post
This is the last time I bother to even read that particular question.

You "fail" in a weight lifting set when you have no longer enough energy to apply force equal with the weight.
You can NOT just say it’s the energy that fails or runs out, that is non scientific, very biased and unfair.

You have no temporary energy left and NO temporary force left. As we are not in this case taking about energy are we ??? So if I cannot lift 400 pounds above my head, you will say I have not enough force, right ??? And if I can lift up 200 pounds 30 times you will say in the end you did not have enough force left right ??? Well actually I did not have {and I am being scientific, non biased and fair here} force “and” energy left, you can’t have one without the other, you “HAVE” to include force and energy when you say I hit momentary muscular failure faster than you.

I ran out of temporary force because I used up all my temporary energy, or/and I used up all my temporary energy because I used up all my temporary force. BOTH are used, and used up. I STILL have energy and force left, but I need to recuperate to get them both back.

Quote Quote by douglis View Post
"Failing" faster with a certain kind of lifting means that with this kind of lifting you spend energy at a higher rate....NOT that you use more force.In all cases the average force is equal with the weight.
Ok if you want to think backwards, tell me “why” I use up my energy faster ??? Or with this kind of lifting why do you think you spend energy at a higher rate ???

More acceleration/force ??? if not what and why ???


Quote Quote by douglis View Post
It's the fluctuations of force that are more energy demanding.That's the only scientific answer you can get.
But this is what I “have” be saying all along, the high fluctuations of force that are more energy demanding, meaning if they are more demanding as you just said, means your forces can not make up or balance out, right.

Wayne
waynexk8
#104
Feb1-12, 06:37 PM
P: 399
Quote Quote by sophiecentaur View Post
Wayne
You still don't get it, do you?
Whatever you 'feel' in your arms and whatever you think that machine is telling you, my points 1,2 and 3 still apply.

1. You can't say it's accelerating constantly all the time. If it were, then it would still be moving at the top. It isn't because, of course, it stops at the top. And, in practical terms, you have no way of knowing without measuring the velocity at very short intervals over the whole of a lift.
Right.

Quote Quote by sophiecentaur View Post
2. For the weight to start at zero velocity and to end at zero velocity then the average force Has to be weight. This may annoy or confuse you and it may not be what you think the machine is telling you but is true beyond any shadow of a doubt. You could ask Sir Isaac Newton himself and he would tell you the same.
Ah, but that’s what I am not saying is not true, meaning you’re not understanding what I am trying to say, I am saying the above is right, I always have.

I am saying that my higher acceleration forces, and they are higher and always higher than the slow, as my higher force on the transition from negative to positive could be as high as 140% but my normal higher forces are say a 100 to your 80, thus higher.

My point is, when you push out a 100 force there is a 100 force/tension on the muscles, right ??? Now you only push out a 80 force there is a 80 force/tension on the muscles, right ???

You have never put a 100 force/tension on the muscle, right ??? So why and how do you think that your 80 force/tension can equal a 100 ??? As 80 = 80 not a 100. It would take far far far longer in time for your 80 to make up the force/tension on the muscles/object

I am saying I am doing more damage with my higher forces, and your lower forces can NOT do the same damage in the same time frame, that’s why the below happens;

1,
I use more energy,

2,
I move the weight more distance,

3,
My muscles fail faster in the faster reps, proving they must be doing more damage,

4,
EMG agrees.

5,
I am NOT saying your questions are wrong, I am just stating my higher impulse, my impulse force with respect to time, YOUR SMALL FORCE applied for a long time can produce then same momentum change as MY LARGE FORCE applied briefly, because it is the product of the force and the time for which it is applied that is important.

Please if you do not agree, all I would like is that you do/can understand what I am just trying to say ??? I am not at this moment in time concerned who is right or wrong, just that you see my point, as it’s quite frustrating when something argues over you, but they are not actually seeing my point, as they keep repeating what I agree with.

No time for the below its late here.


Quote Quote by sophiecentaur View Post
3. You actually don't know what you mean when you talk of "total force" because you are after an arm waving description of what it feels like to do a lift. I really don't know why you won't accept (from not just me but others, too) that your idea can't be stated in Physics.

What you could find out (but only by measurement) would be the maximum force, the total work done on the weights (thats N lifts times weight times height) and the Power developed (dividing the total work done by the time for the whole exercise).

I don't understand why that isn't enough.
All the other acres and acres of figures you have written on these pages have been pretty much wasted. I'd bet that no one has actually read more than a few sample lines of it and then given up.

How can you be so sure that your question is reasonable when, in the same breath, you admit to not knowing much real Physics?

I have seen some of the movies on your website and I am really impressed by your dedication to your sport. You are clearly a bit of an expert on the practical aspects of it and your advice on how to do the exercises and how to body build is, no doubt, correct. But, when it comes to the Physics of the situation, you just have to be much more rigorous and 'go along with the rules'. Those rules say that you are on a fruitless quest and have been talking mostly rubbish. Why are you bothering and why can't you just accept what you are being told? Do you just like a friendly chat - is that what it's all about?

That is a DEAD PARROT!
Wayne
douglis
#105
Feb2-12, 03:00 AM
P: 148
Quote Quote by waynexk8 View Post
This is where you sort of lose me. As you saying ??? The net force on me and the weight = 200N ??? If so I am still with you, but why say the net force on my muscles and the weight ??? AND WHY take 800 from 1000 ??? As we are only concerned with the weight/force on me, my muscles.
I stopped here.It was my mistake to try to make my point with physics equations.It's obvious that you can't follow them.That's not a bad thing but I don't have the time and the patience to explain every single line that I write.

I suggest to leave out physics.We have two push ups studies that examine exactly you're looking for.In physics there's no such thing as "total force" but in biomechanics there's a magnitude called Total Muscle Activation.
Let's discussed them via mail because obviously they're unrelated with physics.


You can NOT just say it’s the energy that fails or runs out, that is non scientific, very biased and unfair.
What makes you think that you're able to judge what's scientific and what's not?
But even common sense tell us that energy runs out and force is applied.Force doesn't run out.It's either applied or not.

You have no temporary energy left and NO temporary force left. As we are not in this case taking about energy are we ??? So if I cannot lift 400 pounds above my head, you will say I have not enough force, right ??? And if I can lift up 200 pounds 30 times you will say in the end you did not have enough force left right ??? Well actually I did not have {and I am being scientific, non biased and fair here} force “and” energy left, you can’t have one without the other, you “HAVE” to include force and energy when you say I hit momentary muscular failure faster than you.

I ran out of temporary force because I used up all my temporary energy, or/and I used up all my temporary energy because I used up all my temporary force. BOTH are used, and used up. I STILL have energy and force left, but I need to recuperate to get them both back.
You can't lift 400 pounds above your head because you don't have the ability to apply that force.
When you "fail" after you have lifted 200 pounds 30 times,even though you have the ability to apply that force,you have no longer the required energy to apply that force.You run out of energy.You didn't run out of force.

Ok if you want to think backwards, tell me “why” I use up my energy faster ??? Or with this kind of lifting why do you think you spend energy at a higher rate ???

More acceleration/force ??? if not what and why ???
Not more acceleration...neither more force.The mean force is the weight which means "the forces balance out...make out" or whatever.Accept that fact.
The generation of force(fluctuations are generation/degeneration cycles) is more energy demanding than the maintenance of force(as if holding the weight).There're biology studies that prove that.
That's a perfectly scientific answer.
sophiecentaur
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Feb2-12, 03:23 AM
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Quote Quote by waynexk8 View Post

Please if you do not agree, all I would like is that you do/can understand what I am just trying to say ??? I am not at this moment in time concerned who is right or wrong, just that you see my point, as it’s quite frustrating when something argues over you, but they are not actually seeing my point, as they keep repeating what I agree with.

No time for the below its late here.




Wayne
The point you are trying to make is not to do with Physics. It's to do with what you feel in your muscles and how you are trying to fit it to some kind of 'Mechanical Science', that you've invented. You have absolutely no idea of what your muscles are doing at the time they're doing it. There is a delay, corresponding to a large fraction of the time of one lift, in what you do and your consciousness of what you did. That's no basis for an experiment because the evidence is fundamentally flawed.

You must have spent hours and hours on this and it really isn't a good way to learn anything about a subject.
This is not uncommon. Many people write posts about their pet approach to some topic and insist on having it explained in their terms only. It so often fails because they are not prepared to start from scratch and get the subject properly sorted out. Douglis has very patiently, point by point, taken you through your problem and you just reply with remarks like:
"Sorry you lose me a little there ??? Equal with g ??? I know what g is, but not sure why you are saying equal with it."
His conclusion would be absolutely blindingly obvious to you if you had taken the trouble of approaching this from the beginning instead of doggedly insisting that your view is the right one. Science doesn't necessarily 'make sense' when you try to reconcile it with ideas which, themselves, don't make sense.
You could have completed a whole GCSE Physics Course in the time you have wasted trying to justify your misplaced views on these threads. If you had, then you would have no trouble understanding this really elementary bit of Classical Science. You would also see how simple Physics can't help you with this 'undefined' question that you keep trying to ask.

As I hinted before, I really question your motives here. I suspect you are just attention seeking.
I'll bet you haven't read all the words in this post, too.
waynexk8
#107
Feb4-12, 06:04 PM
P: 399
Quote Quote by sophiecentaur View Post
3. You actually don't know what you mean when you talk of "total force" because you are after an arm waving description of what it feels like to do a lift. I really don't know why you won't accept (from not just me but others, too) that your idea can't be stated in Physics.
Ok I will be able to except that the total or overall force will not be able to be equated by physics, I just find it odd, as this the below F = Ma seems so easy, but then when I ask for the force for 80 pounds moving 20 inch in .5 or a second, and 80 pounds moving 3.3 inch in .5 of a second, it can’t be done ???

In total or overall force, I mean the muscles only have a temporary limited amount of force before its used up, so let’s say I can lift 200 pounds 10 x at 1/1 = 20 seconds, then I could not lift it a full rep again, but maybe half a rep, but let’s forget about the half a rep, could not we work out how much force I have, or much I have used ???

F = Ma.
200kg and an Acceleration of 20m/s or 10m/s then we can work out the Force pushing the car by multiplying the weight by the Acceleration like this,

Fast rep,
200 x 20 = 4000N.

Slow rep,
200 x 10 = 2000N

Yes I know for my reps there will be a deceleration, but don’t see how the above 2000N can make up or balance out the 4000N ???

PLEASE, could explain this too me. So this means that I would have to use a force of 4000N to be able to move the 200kg 20m in 1 second, so that means I would have to apply the 4000N for 1 second only for it to move 20m in 1 second ??? And what ???


Quote Quote by sophiecentaur View Post
What you could find out (but only by measurement) would be the maximum force, the total work done on the weights (thats N lifts times weight times height) and the Power developed (dividing the total work done by the time for the whole exercise).
I don't understand why that isn't enough.
Ok Maximum force would be ok for a start, how would you do that please ??? And total work done on the weights.

Believe it or not I can work the power out quite easy, that’s one of the first things that got me back interested in physics. I know this is like 1 and 1 too you, but hope I am doing it right here ???

Calculate how much power I would be used on both rep speeds. Distance weight moved 1.85 M.

Determine the force we will need to figure out what the weight of the barbell is (W = mg = 91 kg x 9.81 m/s = 892 kg.m/s or 892 N). Now, if work is equal to Force x distance then, U = 892 N x 1.85 m = 1650 Nm.

We can calculate that lifting a 200 lb barbell overhead a distance of 1.85 m required 1650 J of work.

Let us only add up the positive part of the lift.

The concept of power however, takes time into consideration. If for example, it took .5 seconds to complete the lift, then the power generated is 1650 J divided .5 s = 3300 J/s.

If it took 2 seconds to complete the lift, then the power generated is 1650 J divided 2 s = 825 J/s.

Slow set,
825 x 6 reps = 4950Joules.

Fast set,
3300 x 25 reps = 82500Joules



[QUOTE=sophiecentaur;3740156]All the other acres and acres of figures you have written on these pages have been pretty much wasted. I'd bet that no one has actually read more than a few sample lines of it and then given up.

How can you be so sure that your question is reasonable when, in the same breath, you admit to not knowing much real Physics?

Quote Quote by sophiecentaur View Post
I have seen some of the movies on your website and I am really impressed by your dedication to your sport. You are clearly a bit of an expert on the practical aspects of it and your advice on how to do the exercises and how to body build is, no doubt, correct.
Big thank you for that as at first I thought you was trying to make out I was a crank, as imagine you going to a place where no one knows you, and they say you know knowing of physics and don’t know what you’re talking about. But I have been training for nearly 40 years, and the Wrought Iron is my business, thx again for saying that, as was getting a bit up tight.

Quote Quote by sophiecentaur View Post
But, when it comes to the Physics of the situation, you just have to be much more rigorous and 'go along with the rules'. Those rules say that you are on a fruitless quest and have been talking mostly rubbish. Why are you bothering and why can't you just accept what you are being told? Do you just like a friendly chat - is that what it's all about?

That is a DEAD PARROT!
Ok yes I will have to go along with the rules, but I know I go on about it, but the EMG ??? Or do you know what a force plate is ??? I imagine so, what if I bought one, or got someone to do some tests for me, and just say, and please just say, and I am not saying you are, but let’s just say that like the EMG the force plate readings come back stating the fast do have a higher average force reading, what would you do, would you be very interested, and very interested to find out not how the physics equations were wrong, as they are not, but would you be very interested to find out what variables you left out ???

This debate is HUGE on the internet. Over several different forums, by 1000s of different people, and lots or separate debates, and it’s been going on for well over ten years.

Not that well, back to answer the rest tomorrow.

Wayne
sophiecentaur
#108
Feb4-12, 06:30 PM
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The basic rules of all this are so simply stated that they don't justify all this 'chat'. All the blather is just clouding the issue.
I shall not bother to repeat, yet again, the very few relationships and definitions.
All I can say is that, if you cannot state your question in just a few words with no numbers and just the right terms, used correctly, there isn't an answer. No one wants to read another list of numbers and jargon terms. We have established that it doesn't get us anywhere.


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