Thread Closed

Impulse/force in pounds for the time frame

 
Share Thread
Mar1-12, 08:55 PM   #188
 

Impulse/force in pounds for the time frame


Will get back to jmmccain and Dalespam tomorrow, funny I have two very good high definition cameras.

Wayne
Mar2-12, 07:16 AM   #189
 
No time just now, to read the posts and answer.

Just wanted the state why average force means nothing in this debate

I lift 80 pounds at “any” speed, let’s go for 1/1, {1 second positive and 1 second negative} you all are saying that the average force for 1 repetition, and the average force for a 100 repetitions are the exact same ??? However, we all know that you will exert far more total or overall force doing the 100 repetitions. You will exert a force the same as you do for 1 repetition {forgetting fatigue here} = 2 seconds, for 200 seconds, so its overall or total force output x 200 seconds.

So the question is, why does everyone keep commenting on the average force is the same, when it has no reverence in this debate ??? What we are looking for, is in which repetition speed, in the same time frame, puts the most overall or/and total tensions on the muscles ???

As I have said, as you fail 50% faster using the .5/.5 to the 3/3 using 80% this does mean thet you have put more tension on the muscles faster, right ??? And to put more tension on the muscles, and faster, you will have to use more force, if not please say why you think not ??? PLEASE will someone try to answer this.

Are there anyone out there that thinks if you fail to lift a weight up after say 10 seconds, as you are lifting it faster, that it is not because you have put more tension on the muscles than the slow lifting, if so say why please.

Wayne
Mar2-12, 10:57 AM   #190
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
You were the one who asked what average force was. You also asked about Total Force.
Do keep up!
Mar2-12, 01:55 PM   #191
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
Wayne
Can you quote me a single statement, from anyone else, on this forum or in the communications with others that you have shown us, that indicates what you are talking about makes any sense in terms of the Physics? Everything I have read looks like non-committal and polite put-downs. When will you get the message?
Have you not realised that no one wants to discuss your endless, blow-by-blow descriptions of a lifting session? If you cannot be bothered to condense your questions into a digestible form then I, for one, can't be bothered to read them. I (/we all) have given you all the facts about the very straightforward Physics that relates to the process.
You haven't been prepared to accept it because it "doesn't feel right to you", somehow and you haven't been prepared even to use 'our' vocabulary. Can you be surprised that you aren't getting satisfaction?
Mar2-12, 07:26 PM   #192
 
Quote by DaleSpam View Post
Hi waynekx8, I didn't notice that you were back.

It looks like you are still confusing "work done" and "energy expended" as we discussed last year: http://www.physicsforums.com/showthr...15#post3190515
Hi again Dalespam,

Actually I am not confusing work done and energy expended, "unless" work done means the overall or total force used ??? And we know for a fact that the fast does more work and uses more energy.

Average means nothing in this debate. What I am looking for is the higher overall or total forces used, thus more overall or total force on the muscles, just take this example.

Lift a weight up and down for 10 seconds, lift a weight up and down for 6o seconds, the average force is the same, but lifting the weight for 60 seconds WILL and DOES put more total or overall tension on the muscles, this means the total or overall force was more.

What we WANT to know is the same for lifting the weight up and down 6 times in 6 seconds, and lifting the weight up and down 1 time in 6 seconds.

Now I say without a shadow of a doubt, it’s the fast, and here is why. If you took both repetitions speeds to momentary muscular failure, meaning if you lifted the weights at the two given speeds until you could not move the weight, you would fail about 50% faster lifting the weight the fast way. This can ONLY mean one thing, you put more tension on the muscles faster, thus the muscles failed faster, thus more force must have been used in not only the same time frame, but in less time frame, you also use more energy in the fast, why ??? It’s because your putting out more force and tension on the muscles, if not, why please ??? As no one here is giving me a direct answer, they seem to not want to, or cant ???

Wayne
Mar3-12, 03:45 AM   #193
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
Quote by waynexk8 View Post
Hi again Dalespam,

Actually I am not confusing work done and energy expended, "unless" work done means the overall or total force used ??? And we know for a fact that the fast does more work and uses more energy.

Wayne
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.
Mar3-12, 07:15 AM   #194
 
Mentor
Quote by waynexk8 View Post
Actually I am not confusing work done and energy expended ... And we know for a fact that the fast does more work and uses more energy.
Yes, you are still confusing them. In fact, this quote proves that you are confusing them since you finish with the confused statement that the fast does more work and uses more energy.

The correct statement is that the fast does the same amount of work and uses more energy (i.e. the human machine is less efficient at doing fast work). If you were not still confusing the concepts then you would not still be making the same incorrect statements.

Quote by waynexk8 View Post
What I am looking for is the higher overall or total forces used,
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 [itex]t_i[/itex] to time [itex]t_f[/itex] is:
[tex]\overline{\mathbf{f}}=\frac{\int_{t_i}^{t_f} \mathbf{f}(t) \, dt}{t_f-t_i}[/tex]

Please provide a similar rigorous definition for total or overall force.
Mar3-12, 07:21 AM   #195
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
@Dalespam
I see you are being drawn into this. Beware - madness lies there.
Mar3-12, 07:27 AM   #196
 
Mentor
Quote by sophiecentaur View Post
@Dalespam
I see you are being drawn into this. Beware - madness lies there.
Thanks for the warning sophiecentaur, but I have worked with wayne before, same topic different thread. I will only stick around while it is fun.
Mar3-12, 07:32 AM   #197
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
It's quite incredible how he bounces back with the same question, which, in itself, has no meaning.
Mar3-12, 07:51 AM   #198
 
Mentor
I was trying to think of weight lifting analogy to describe his behavior in terms that he could understand, but my weight lifting vocabulary is fairly limited.

Basically, I want to get across the point about how stupid I would be if I were to go to him and a bunch of other weight lifting experts and ask for their advice on a weightlifting problem and when all of them tell me the same thing I then ignore their expertise and continue doing the opposite. Particularly if they are united in their opinion and persist in their opinion after detailed questioning.

They are experts in weight lifting, I know that I am ignorant on the subject, and since they all agree with each other, and my opinion disagrees with them, the only reasonable thing to do is to recognize that my uninformed opinion is almost certainly wrong and try to understand their advice.

Also, it wouldn't be helpful for me to call a weight machine a dumb bell, nor would it be helpful for me to talk about things they have never heard of like the supercalifragilistic rep without describing in detail what I mean by that. Furthermore, if they corrected me on my incorrect use of the term weight machine and dumb bell and I continued to use it incorrectly (for years) they would reasonably become frustrated.
Mar3-12, 08:42 AM   #199
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
Precisely. For "force" substitute "bannana" and his physics would make the same amount of sense.
Mar3-12, 12:14 PM   #200
 
Quote by jmmccain View Post
Wayne,

May I suggest an experiment? Do you have access to a bathroom scale and two video cameras?
Hi jmmccain,

Yes,

Quote by jmmccain View Post
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 View Post
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 View Post
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
Mar3-12, 12:22 PM   #201
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
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.
Mar3-12, 12:28 PM   #202
 
Quote by sophiecentaur View Post
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 View Post
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 View Post
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
Mar3-12, 12:59 PM   #203
 
Recognitions:
Gold Membership Gold Member
Science Advisor Science Advisor
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.
Mar3-12, 01:43 PM   #204
 
Hi sophiecentaur, you should get this debate and what I am getting at if you read 8, you too D.

Quote by sophiecentaur View Post
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 View Post
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 View Post
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.

Quote by sophiecentaur View Post
I'm still waiting for your detailed reply about Total Speed.
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
Thread Closed

Similar Threads for: Impulse/force in pounds for the time frame
Thread Forum Replies
most force/strength used in the same time frame General Physics 69
Impulse question about Force and time Introductory Physics Homework 2
Force vs. time graph (Impulse) Introductory Physics Homework 16
Impulse and Force-Time Graph Introductory Physics Homework 2
Velocity as a function of force/impulse/time. Introductory Physics Homework 2