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DaleSpam
#226
Mar7-12, 02:48 PM
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P: 16,985
Quote Quote by waynexk8 View Post
Very right of you, I do agree, but please I do find this hard at times, but if you tell me something I said wrong, I will try and remember, but if for some reason I get it wrong of forget, please tell me again and I will make a note. So sorry all, I am trying, but the most annoying is when people do not answer my writings, unless you have, and I have not got to them

Yes see what you mean, could you point me out on the things I am getting wrong please.

Total get your point, and it’s a good one, and I do need to concentrate on this more.
Hi waynexk8, the first thing that you need to correct is that there is no such thing as total force. There is impulse which is defined as:
[tex]\mathbf{I}=\int_{t_i}^{t_f} \mathbf{f}(t) \, dt[/tex]
Impulse has units of momentum, not units of force.

There is also average force which is defined as:
[tex]\overline{\mathbf{f}}=\frac{\int_{t_i}^{t_f} \mathbf{f}(t) \, dt}{t_f-t_i}[/tex]
Average force does have units of force.

Second, you are under the mistaken impression that the impulse is higher if you do a rep faster. This is incorrect. The impulse for one rep depends only on the weight and the amount of time, so one slow rep (10 s) might have the same impulse as 5 fast reps (2 s each). Similarly, you seem to be under the impression that the average force over a rep is higher if you go faster. This is also incorrect. The average force for one rep depends only on the weight. Notice that there is a close relationship between impulse and average force.

Personally, I think that the question you should be asking is the following:
"What different physical quantities are in fact higher in a fast rep than in a slow rep?"