Impulse/force in pounds for the time frame

by waynexk8
Tags: frame, impulse or force, pounds, time
 PF Patron Sci Advisor P: 10,120 Precisely. For "force" substitute "bannana" and his physics would make the same amount of sense.
P: 399
 Quote by jmmccain Wayne, May I suggest an experiment? Do you have access to a bathroom scale and two video cameras?
Hi jmmccain,

Yes,

 Quote by jmmccain Set up one camera to record the scale reading and perform your various fast and slow exercises. Afterwards, view the recording frame by frame and plot the scale reading for each frame (like douglis' graph, but it won't look the same). Don't forget to subtract your own weight from all the readings. This will rather conclusively demonstrate the difference in forces.
How do I do this please ???

 Quote by jmmccain Add up all the readings for a repetition (again, adjusted for your weight). Then divide by the number of frames over which the readings were observed. This will be the mathematical average and should be very close to the weight you are lifting. How close depends upon how well the experiment is performed.
However, as I said, there is a problem using average force, as if you do 1 repetition at any speed, say 1/1, that’s 1 second up and 1 second down, you will get the same average force if you do 1 repetition or a 100 repetitions. So average will not tell us anything, or will it ???

1 repetition = 100 force up and 60 force down, 100 + 60 = 160/1 = 160, average force = 160.
100 repetitions, 100 x 100 = 10000, 100 x 60 = 6000, 10000 + 6000 = 16000/100 = 160.

Some the average force is the same, BUT we all know that the doing the 100 repetitions is going to use more muscle force and put more tension on the muscles

I made a thread on this and told D. this average means nothing in this debate, but he and some others still insist it does, but can’t not say ???

 Quote by jmmccain The second camera is used to record the movement of the weight with a tape measure, or other suitably visible scale, in the background. Again, go through frame by frame and plot the position of the weight. This should look something like douglis' graph. Next, plot the change in position from one frame to the next (velocity). Next, plot the change of this change (acceleration) from one frame to the next. This third plot should look just like the first plot of the scale readings. F = ma The first plot of the scale readings is force. The last plot is acceration. Since the mass doesn't change, the two remain proportional to each other and the plots should be very similar. The scale and cameras won't lie. If you need help decipering the results and making the appropriate plots, well, I may be busy, but there are others around who will help.
This seems very interesting, and have heard of this before, but not sure this will give use the right results. PLEASE what results will this tell us, I dont understand what this will show ???

Wayne
 PF Patron Sci Advisor P: 10,120 Do you guys know about sampling theory? To do this investigation to any satisfactory degree (to avoid misleading results) you will need a slo-mo camera, at the very least, and a set of scales with ms response times. I don't think the average bathroom scales has been designed that way. Also, you would need many samples and some good data analysis. If it were really as trivial as you suggest, it would be an AS level Physics practical. The last thing we would want would be a naff experiment that could yield results either way. If they went the wrong way, we could never ever convince Wayne that he's barking up the wrong tree. And what about the 'total speed' question, Wayne? If you can't justify total speed then you can't justify total force. I await your specific and detailed response.
P: 399
 Quote by sophiecentaur I'd advise not getting too involved with this. All your suggestions have been made many times before, in this thread and earlier threads. Wayne does not believe in the accepted ideas of Physics. He has his own models and vocabulary of Physics.
I have heard of this before, but never knew how to do it, and not sure what the results will be ???

Wayne does believe in accepted ideas of Physics, I don’t understand why you say that, what I am saying, and have proven, that the avenger force can show us “nothing” unless you think is can, if so, please say what ???

 Quote by sophiecentaur Also, your thought experiment on the bathroom scales would not show the sampled forces accurately or frequently enough to convince Wayne. There would be errors which he would jump on and claim that the experiment showed him to be right. The scales and camera would lie in practice unless a much more sophisticated system were used.
I would not jump on small errors ???

You a D. have dismissed a real World EMG test, but you cannot say why, I think because it shows what I say is right, and what you cannot work out with physics, in that there HAS and IS more force in the faster repetitions in the same time frame. Or do you and D. think that I fail faster when doing the faster repetitions because there is less force output by the muscles, and less tension on the muscles ??? If so please say and explain why you think that or other, the point is you do fail 50% faster, thus there can ONLY be ONE reason for this, you produce for force in the same time frame, putting more tension on the muscles, making the muscles fail faster, if you do not think this, please say why ???

 Quote by sophiecentaur In any case, what you say would only apply to free lifts and not to exercises on machines that introduce friction. That also confuses Wayne and strengthens him in his misconceptions.
This does, or cannot confuse me; I train on free weights, Nautilus machines, and round circular pulleys, and have made many of my own machines and know the effects of all of them on the muscles. This debate is basically on free weights, with a machine doing the exercise or a Human.

Wayne
 PF Patron Sci Advisor P: 10,120 You so much do not believe in the ideas of conventional Physics, Wayne, that you even refuse to use the correct terminology. You seem to ignore the fact that everyone agrees that the Maximum force for fast lifts must be higher because of the acceleration - that's proper Physics. Just imagine - to change tack- that you had replaced your arms with a strong pair of springs of the appropriate stiffness. If you lifted the weights to your normal lift height and then let go, the weights would go down and up and down and up for a long time until friction became apparent. No work done at all if you recover the weights when they are at the top of their bounce. That's Physics. It's true and it just doesn't represent a good model of your muscles. If you used a stiffer spring, the oscillations would be at a faster rate or, for a less stiff spring, the oscillations would be at a slower rate. No difference, in any of the cases, with the energy involved (total = zero). I'm still waiting for your detailed reply about Total Speed.
P: 399
Hi sophiecentaur, you should get this debate and what I am getting at if you read 8, you too D.

 Quote by sophiecentaur You so much do not believe in the ideas of conventional Physics, Wayne, that you even refuse to use the correct terminology.
Please could you try and answer my questions, I am not interested in a mocking match, and you not answering seems to show you are unsure.

1,
You a D. have dismissed a real World EMG test, but you cannot say why ??? You seem to be against RMS way, but cannot say why ??

2,
Do you agree that a muscle that if I do 10 repetitions at 1/1 = 20 seconds, and 1 repetition at 1/1 = 2 seconds. That the 10 repetitions will use more overall muscle force, more total muscle force, longer muscle force ??? If and when you and D. understand this question, you will then understand my question, as from what you and D. say, I am sure you don’t understand. [b]As I fail faster in the faster repetitions, does that not tell you anything ???

3,
I 100 physics had a debate, and did extensive tests, and all agreed I was right, would you be able to say I was right, or are you too deep in ???

4,
Do you see where/why average force means nothing in this debate ??? If you do 1 repetition at any speed, say 1/1, that’s 1 second up and 1 second down, you will get the same average force if you do 1 repetition or a 100 repetitions. So average will not tell us anything, or will it ???

1 repetition = 100 force up and 60 force down, 100 + 60 = 160/1 = 160, average force = 160.
100 repetitions, 100 x 100 = 10000, 100 x 60 = 6000, 10000 + 6000 = 16000/100 = 160.

Some the average force is the same, BUT we all know that the doing the 100 repetitions is going to use more muscle force and put more tension on the muscles

Do you see what I mean ???

5,
Do you and D. think that I fail faster when doing the faster repetitions because there is less force output by the muscles, and less tension on the muscles ??? If so please say and explain why you think that or other, the point is you do fail 50% faster, what both use 80% on the repetitions, thus there can ONLY be ONE reason for this, you produce for force in the same time frame doing the faster repetitions, putting more tension on the muscles, making the muscles fail faster, if you do not think this, please say why ???

6,
You use more energy in the faster, why ??? As immediately you move faster, using more accelerations using more force, you use more energy, are you saying you use more energy because you don’t use more force ???

7,
You move the weight 6 times further in the same time frame, you have to use more force to move a weight further in the same time frame, if not, how do you move the weight further if by not using more force/accelerations ???

 Quote by sophiecentaur You seem to ignore the fact that everyone agrees that the Maximum force for fast lifts must be higher because of the acceleration - that's proper Physics.
I am not ignorant to that, I know it, and I know everyone else knows it, this is not the debate.

Let me try and explain again.

8,
We are the exact same strength, we are moving 80% of our 1RM, {Repetition Maximum} We are both going to move this weight until momentary muscular failure, meaning we are going to move the weight until we cannot lift it again.

I use my 100% maximum force ALL the time, which is a 100 pounds, you on the other hand only use 80% of your force all the time.

I hit momentary muscular failure about 50% faster than you do, because I am using 100%, but you are not using 100% you are using 80% yes 80%, and using 80% consistently for the exact same time as me moving the weights, {lets cal that 30 seconds} HOW can you think or claim that you ONLY using 80% consistently for the same time frame as I using 100% consistently, will use the same overall or total force output ??? Or will make the same momentum/movement change ???

1,
I use 100% force for 30 seconds.

2,
You use 80% force for 30 seconds.

3,
How can using 80% of force for 30 seconds be the same as using 100 force for 30 seconds ??? Please state why.

 Quote by sophiecentaur Just imagine - to change tack- that you had replaced your arms with a strong pair of springs of the appropriate stiffness. If you lifted the weights to your normal lift height and then let go, the weights would go down and up and down and up for a long time until friction became apparent. No work done at all if you recover the weights when they are at the top of their bounce. That's Physics. It's true and it just doesn't represent a good model of your muscles. If you used a stiffer spring, the oscillations would be at a faster rate or, for a less stiff spring, the oscillations would be at a slower rate. No difference, in any of the cases, with the energy involved (total = zero).
Not sure what you mean there ??? Or are getting at, as I HAVE to use force and energy on the way down, or lowering the weight as well as lifting.

I answered that, is a different quantity, but if you want I will come up with a better one, please try and answer 8, and the rest, please you too D. and anyone else here.

Wayne
 PF Patron Sci Advisor P: 10,120 Nothing more from me until you answer my 'simple' question.
P: 148
 Quote by waynexk8 I use my 100% maximum force ALL the time, which is a 100 pounds, you on the other hand only use 80% of your force all the time. I hit momentary muscular failure about 50% faster than you do, because I am using 100%, but you are not using 100% you are using 80% yes 80%, and using 80% consistently for the exact same time as me moving the weights, {lets cal that 30 seconds} HOW can you think or claim that you ONLY using 80% consistently for the same time frame as I using 100% consistently, will use the same overall or total force output ??? Or will make the same momentum/movement change ??? 1, I use 100% force for 30 seconds. 2, You use 80% force for 30 seconds. 3, How can using 80% of force for 30 seconds be the same as using 100 force for 30 seconds ??? Please state why.[/b] Wayne
Everyday you prove that you don't have a clue what everybody is trying to explain to you.

YOU DON'T USE 100% FORCE FOR 30 SECONDS.
You use more force than the weight when you accelerate and less force than the weight when you decelerate.For these 30 seconds....either you lift fast or slow....the average force per second is the weight.

Stop saying nonsense like "average force means nothing in this debate".It's the same average force per second and this answers EVERYTHING everything you asked.
The effect of force over time(which is what you described as "total/overall force") is identical.
P: 148
 Quote by DaleSpam Let f(t) be the force exerted by the human on the weight at time t. Please define overall or total force in terms of f(t). For example, average force from time $t_i$ to time $t_f$ is: $$\overline{\mathbf{f}}=\frac{\int_{t_i}^{t_f} \mathbf{f}(t) \, dt}{t_f-t_i}$$ Please provide a similar rigorous definition for total or overall force.
Hi DaleSpam,
he described the "total/overall force" as the effect of force over time so the ∫f(t)dt is exactly what he means.
.....and of course is the same regardless the lifting speed since the average force is the weight in any case.
 PF Patron Sci Advisor P: 10,120 Let's be accurate about this: ∫f(t)dt (a definite integral) is the impulse (change of momentum), which varies, depending which part of the lift cycle your integration extends. There is greatest impulse during sections of the fastest repetitions because the velocity change is greatest. I wouldn't accept some cranky alternative language from douglis or dalespam so why should I accept it from Wayne? Some of the published stuff uses terms similar to what he uses but makes it clear that it is only over the lift part. I think Wayne is over / mis interpreting a lot of it because his terminology is so inaccurate that I don't think he can be understanding the true messages. Funny thing is that I find little to argue with in any of the references I've looked at. Yet he seems to find a great deal of support within the same texts. They obviously steer clear of making non-physics gaffs because they are not interested in Waynes "physics approach". They clearly know the business better than he. I can see that he reckons he works harder doing faster lifts but I can't see how he can assume that he knows what his muscles are doing whilst he's lifting. That is what the EMG tries to do - but his interpretation of those seems a bit fanciful, to be honest (and polite). I think his posts must qualify for a record for the consistently long yet vague posts I have read on PF.
Mentor
P: 15,620
 Quote by douglis he described the "total/overall force" as the effect of force over time so the ∫f(t)dt is exactly what he means.
Ah, ok. That is a defined term in physics, called impulse:
http://en.wikipedia.org/wiki/Impulse_(physics)

Edit: I see sophiecentaur already mentioned it.

I just want to point out that impulse does not have units of force, it has units of momentum. Assuming that we are talking about the impulse over one full rep then the change in momentum is 0 so the impulse on the weight is 0.

The only two forces acting on the weight are gravity and the human, so the impulse provided by the human is equal and opposite to the impulse provided by gravity. So, the impulse is equal to the weight times the duration of the rep. Therefore the human provides a larger impulse on a slow rep than on a fast rep.

waynekx8, if by "total force" you mean "impulse" then it is greater for a slow rep than for a fast rep. If you mean some other quantity then please define it explicitly.
P: 148
 Quote by DaleSpam The only two forces acting on the weight are gravity and the human, so the impulse provided by the human is equal and opposite to the impulse provided by gravity. So, the impulse is equal to the weight times the duration of the rep. Therefore the human provides a larger impulse on a slow rep than on a fast rep. waynekx8, if by "total force" you mean "impulse" then it is greater for a slow rep than for a fast rep. If you mean some other quantity then please define it explicitly.
That's the whole point of the discussion and it's been explained to Wayne many times.
Regardless if you lift the weight fast or slow for 30 seconds....the "total/overall" force is always the same and equal with gravity's impulse for that duration.
P: 399
 Quote by sophiecentaur That statement is meaningless. There is no "debate" possible on that basis. Why not do us all a favour and use PF language? Total force is as daft as total speed. Come to terms with that.
Well how as a physicist would you define/call it ???

I have said this many times, to move a car 1 mile in 30 minutes, with the force of a Man pushing, you will “have” to use a certain amount of force, right ??? As if you knew the exact amount of force, and you used less force, you would not move the car 1 mile in 30 minutes, so you must be used a certain amount of force for 30 minutes. And if you moved the car 1 mile in 45 minutes, you “would” be using less overall or total force, yes ???

I am not being sarcastic here, but when I do ??? It means I am asking you a question if you agree of not, and it’s very hard for me if you don’t answer, so please if you agree or don’t agree, please state why.

How can we add up total or overall speed. Right, let’s take an easy one, and measure speed by every .1 of a second. The object is moving at a constant speed of 100mps, so we could say JUST for arguments sake, the total or overall speed for 10 seconds = 1000. This is like they do all over the World in powerlifting, weightlifting, bodybuilding and athletics, if they have done a training day on squats and bench press; they say they have moved a certain amount of tonnage or poundage in a day. So if they did 10 x 10 squats and 10 x 10 bench press with 200 pounds, they will say they have moved 4000 poundage in one day, and if they want to get very technical, they will work or the exact amount of time they moved this poundage, and say they moved 4000 in 200 seconds, thus producing more power and force in less time than the week before hopefully.

But speed is a different thing, F = ma. If we work out the forces at work on some objects, it will be by multiplying the weight of the object by the acceleration of the object right.
The force at work on a cart pulled by a horse, the weight of the cart is 400 and an Acceleration of 20m/s to work out the Force pushing the cart is by multiplying the weight by the acceleration, 400 x 20 = 8000N in 1 second, if an acceleration of 40m/s its 400 x 40 = 16000N in 1 second. The more seconds you push the weight, the longer in seconds you will have to use this same force, as you cannot push the same weight for 10m with just using a 1 second push of 1600N can you ??? Seems like some are forgetting to add in the force with respect to time, which equals more distance the weight moved, and longer the force is applied ???

Wayne
 Mentor P: 15,620 The more seconds you push with a fixed force, the larger the impulse of the push. Therefore a slow rep will have a greater impulse than a fast rep.
P: 148
 Quote by DaleSpam The more seconds you push with a fixed force, the larger the impulse of the push. Therefore a slow rep will have a greater impulse than a fast rep.

....consequently,when the same average force is applied for the same duration the impulse is always the same regardless if you lift fast or slow or if you do more or less reps.

That's the whole story that took so many pages and so many threads.
PF Patron
P: 10,120
 Quote by waynexk8 Well how as a physicist would you define/call it ???
I'd call it Impulse or Work Done or whatever else I actually meant. Your problem is that you haven't really got beyond the stage of deciding what you really want to know or what you mean. We have all told you answers that could apply for a range of things that you could mean. (Please please don't give us another story to illustrate what you mean - I think I shall run out screaming at another mention of Rep Rate)

 I have said this many times, to move a car 1 mile in 30 minutes, with the force of a Man pushing, you will “have” to use a certain amount of force, right ??? As if you knew the exact amount of force, and you used less force, you would not move the car 1 mile in 30 minutes, so you must be used a certain amount of force for 30 minutes. And if you moved the car 1 mile in 45 minutes, you “would” be using less overall or total force, yes ???
You start of talking about a force then you suddenly jump to "overall or total force". That's where the nonsense creeps in. Force is Force and it means just one thing. If the man pushed the car for 30 minutes, then I am assuming this would be at a steady speed on a flat road, just against friction??? What you could say is that the WORK he did was Force times the distance the car traveled.
If he pushed with less force, then the car would not be going as fast and it would cover less distance. The WORK done would be the new force times the new distance.
You seem to have some objection to describing things that way. Why? It's the way that the rest of us talk because it fits in with the rest of Physics.
You would be doing less WORK but your description, involving the word 'force' makes no sense.
 I am not being sarcastic here, but when I do ??? It means I am asking you a question if you agree of not, and it’s very hard for me if you don’t answer, so please if you agree or don’t agree, please state why.
I have done that for you.

 How can we add up total or overall speed. Right, let’s take an easy one, and measure speed by every .1 of a second. The object is moving at a constant speed of 100mps, so we could say JUST for arguments sake, the total or overall speed for 10 seconds = 1000.
Here you go again with 'total speed'. What you seem to mean here is that the DISTANCE is 1000 (100m/s for 10s). Speed times time = distance, doesn't it? So "total speed = distance" for you? Not good enough. You want to join the Physics club and get answers. Club rules apply, I'm afraid and you have to use the right terms or no one will understand what you're on about.

 This is like they do all over the World in powerlifting, weightlifting, bodybuilding and athletics, if they have done a training day on squats and bench press; they say they have moved a certain amount of tonnage or poundage in a day. So if they did 10 x 10 squats and 10 x 10 bench press with 200 pounds, they will say they have moved 4000 poundage in one day, and if they want to get very technical, they will work or the exact amount of time they moved this poundage, and say they moved 4000 in 200 seconds, thus producing more power and force in less time than the week before hopefully.
No - they did more WORK and possibly in less time. This means more Power. The details of what forces were involved are not included in their statement.

 But speed is a different thing, F = ma. If we work out the forces at work on some objects, it will be by multiplying the weight of the object by the acceleration of the object right. The force at work on a cart pulled by a horse, the weight of the cart is 400 and an Acceleration of 20m/s to work out the Force pushing the cart is by multiplying the weight by the acceleration, 400 x 20 = 8000N in 1 second, if an acceleration of 40m/s its 400 x 40 = 16000N in 1 second. The more seconds you push the weight, the longer in seconds you will have to use this same force, as you cannot push the same weight for 10m with just using a 1 second push of 1600N can you ??? Seems like some are forgetting to add in the force with respect to time, which equals more distance the weight moved, and longer the force is applied ??? Wayne
Speed is a different thing, is it? But Maths applies to everything. The word 'total' means adding things together, whether it's cabbages or Joules. Some things just can't be 'added together' and adding speeds-at-different-times is as much forbidden as adding forces-at-different-times. This isn't poetry or stream of consciousness - it's strict and rigorous stuff.

Sorry, the last bit just reads like ramblings. I can't see what you're getting at except to tell me a story in non-technical terms. Why does a horse and cart have to be different from a man and a car? The man and car scenario says it all.

You are getting some damned good value out of all this you know.
Mentor
P: 15,620
 Quote by douglis ....consequently,when the same average force is applied for the same duration the impulse is always the same regardless if you lift fast or slow or if you do more or less reps.
Agreed.