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Mechanical Advantage at the Gym

william watts

william watts

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Central valley, calif.
I am so out of shape I can hardly lift a sheet of plywood anymore, so I'm headed back to the gym, with a personnel trainer this time. He directs me to different excerise machines, tells me the number of reps, amount of weight and gives encouragement, what a guy. We got into a discussion on how much weight is actually being lifted when the lifting cable passes over several pulleys and makes a convoluted path to the weight. He and his training buddies are counting the number of pullys, the amount of weight, the length of cable and who knows what all to make that calculation. I explained to him I seem to recall the MA can be determined by the ratio of the length the pulling cable moves to the length the weight is lifted. It makes no difference the number of pullys, the cable path, none of the complicated stuff they came up with. I also said I would ask someone who would know for sure. Anybody?

Bill
 
I suppose one can wonder about all that kind of stuff. To me the point of the evolution is to work out, build up muscles, build up energy and stamina. I have my own weight machine and I don't worry about what the actual weight is. In fact I don't care. I know that supposedly the individual plate is supposed to be 10 pounds, so when I am bench pressing 15 of them, that's supposed to be 150 pounds. If it's not, I am sure it's close. If not it's certainly good enough for me. I certainly don't know how many foot pounds or whatever the measurement is of the squeezer thing I use to keep the grip up to snuff. All I know is that doing what I do for workouts is that I can pickup a sheet of 1/2" plywood with one hand and walk around with it for a bit. Hard to keep a good grip on it. The weight certainly isn't the problem. Oh, well. I find somethings are for doing not analyzing.
 
I do my best to stay in the best shape I can for many reasons. But you can't just do it when it suits you. It's an ongoing thing. Maybe it's a Marine thing that was beat in my head, I can't say. All I know is that if I exercise, I feel better. Doesn't make me look better because I am ugly, worked hard to get that way and am proud of my efforts. It helps me think better (I think) so therefore I am less likely to screw something up. I recommend exercise to anybody. Doesn't have to be weights. All kinds of other exercises one can do. Also helps with my battle of the bulge which I cannot say I am firmly winning but at least I am trying. :D Gotta stay away from them thar M&M's and Reese's Peanut Butter Cups.
 
When I read this thread, my thoughts went to Archimedes...
Give me a lever long enough and a fulcrum to put it and I shall move the world.

I figured you were looking for ways to cheat, lifting weights, with as little effort as possible, to get out of the benefits, and fulfill some bet.
 
I figured you were looking for ways to cheat, lifting weights, with as little effort as possible, to get out of the benefits, and fulfill some bet.[/QUOTE]

My curiosity was because the weights appears to be moving faster than the cable I was pulling on. That lead me to thinking about mechanical advantage on these machines. I do enjoy the workout and suppose the amount of weight makes no difference as long it's sufficient to achieve results.

Randell, not trying to cheat and hope I am not being mislead on the amount I am lifting, just for my own satisfaction. Still curious.

Bill
 
Go to your library and look at the catalogs for sea going equipment. I cannot remember the names of the companies. Many of them will have diagrams showing the pully/cable relationship and simple formulas to figure out energy expended and results achieved. Or just Google pulleys or sheaves (I have never done the Google bit. However I would bet a heck of a lot Google has the answers.)

As Glenn would say, "Google is your friend dad."

Enjoy,
JimB
 
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