General > General Technical Chat
Physics Question - ma = mg
TimFox:
The answer for calories burned by different physical exercise routines is not to be found in physics, but in physiology.
RJSV:
As to the question, about finding an equivalence between calories for an hour lifting weights VS an hour on treadmill, I recall watching a researcher monitoring a face mask, breathing hose. I think the scientists use the oxygen consumption to get parameters related to calories consumed. My guess, also, is there might be some other processes...ie Pathelogical that allow short bursts (of physical performance) in absence of correlation with oxygen consumption.
Oxygen consumption, my speculation, would be able to be directly correlated, with the whole cellular energy equation, almost literally molecule by molecule.
I think there must be ways of answering your question, assuming you get all the circumstances for comparing the two excercise activities.
For a similar reasoning, I probably would not look at a person's body weight (changes), as that could get complex. My guess is that body water loss, sweat, would make exact calorie studies hard to control, just solely on gross weight.
Perhaps, there are military conducted studies, that would supply those performance comparisons.
- Rick B
CatalinaWOW:
Bostonman, don't take this negatively, but you are on a fool's errand. I am not challenging your intelligence or your knowledge of physics or your ability to learn. I am sure that after enough work and study you could separate out the actual work performed in the two activities (note that in the pure physics sense neither involves any work since the runner on the treadmill ends in the same state he began, and the weights also return to their original position). Work being defined as the integral of the scalar force*distance for the two activities. You can sort out all of the inefficiencies in the biological production of that force and distance. Determine the base consumption and the changes in base consumption due to the activity. Figure out how to adjust for the differences in size and physiology between you and the guy you are comparing with. And in the end it will mean nothing. The other guy won't be convinced, and you probably won't either unless the answer turns out in your favor.
The only real answer when dealing with a question of the type you are discussing is what works for you. Which has little or nothing to do with physics. And which answer trumps all the gym instructors, exercise books and other advice on the subject.
bostonman:
I wouldn't and didn't get offended at all.
This thread seemed to turn into more general conversation about everyday physics and maybe I got too comfortable tossing out questions. You're correct, I'm sure I can open plenty of physics and body training books, but sometimes just talking to people helps weed out the confusion. Books go only so far which can sometimes cause limitations in learning.
In some cases this thread went way beyond general mass and acceleration, and other times it seemed to be just general discussion that helped clear confusion.
It's possible I just got too comfortable continuing to talk thinking it was all general discussion while others were providing answers in hopes of ending the thread with a final answer.
CatalinaWOW:
If you want an interesting example of everyday physics think of driving a car. Moving along at constant speed you approach a stop sign. What is the optimum braking profile?
First step, define optimum. Shortest arrival time? Constant deceleration? Minimum jerk?
The, assuming brake friction is constant over time and wheel rotation speed, what pressure profile is required to achieve it.
Simple problem with much meat.
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