Is 7-ups physics theory correct?

I just read 7-ups theory on the V-stretch. This is it cut and pasted
“a 10 pound force suspended from a cord exerts only 10 pounds of force within the fibers of the cord. BUT anchor the cord from 2 ends and place the 10 pound mass in the center….and the tension within the cord increases very greatly. For example, you may hang from a clothes line tied to a tree branch. But if you try to hang from the same cord when it is stretched between 2 clothes line poles, it will break under your weight. The tension within the clothesline exceeds the tensil strength of the rope. That is the theory.”

I will have to read through some physics books again but I do not think this is correct, I cant understand how the rope will break easier on 2 line poles with the same weight. Maybe my interpretation is wrong. I would like to do more calculations to see what angles are best and the possibilities of several weights going up and down like a system of pulleys. As a manual stretch you are limited at the end by the max force you can hold, so what arrangement of other weights is best? Some body builders may tell us what arm position is best for long holds of equivalent weights.

I am by no means saying it doesnt work, I have done the Vstretch and it does feel like a lot more strain on the ligs.

When you’re just stretching your dick the force is (somewhat) evenly distributed over the area pi*r^2 with r being the radius of your dick.

When doing a v-stretch the force is distributed over the area of your finger in contact with your dick 2*r*(width of your finger). Which is less area so more force per area. If you take in consideration your finger is roundshaped as well as your dick it would even increase the force per area for the center.

I understand there is more force per area (more pressure) but is this what we want? If that is the case we would press down with a thin skewer. Reminds me of the old question would you prefer a big wrestler standing on your stomach or a slim woman in stilletoes. A good way to measure the actual stretch power would be to get and elastic band or bungee cord, pull it as hard as you can and add weights along it and see if it increases in length any more.

It tells you can put similar force on your dick by doing v-stretches with your finger as you get from hanging (heavy) weights off your dick.

7-ups basis is vectored force. Vectored force is very real but the example of the cord between stationary points is a simplification of the picture, things change when you take into account elasticity and the complementary vectored force on the arms, shoulders etc. The hand performing the initial grip has limited ability to withstand any force unlike a stationary point, the same follows for the arm supplying the mid-point force.

It is an extremely effective means of supplying force for a stretch and any explanation that is aimed at a wide audience has to be simplified to some extent.

If supplying the force straight armed you are also able to leverage the power of the shoulder more effectively. Doing an inverted/straightword V-stretch over/under a stationary point can also be an effective way of maximising force and the V-stretch hanging variant is getting closer still to two fixed points.

Wow! Mem your my hero of the day with that explanation.

I have tried searching for some sites but can’t find a good one on pulley systems. I have realised I sold my old books which had info. I understand vectored force but am a bit rusty on the whole system of particles theory. It is easier to pull a car by having a rope attached directly at the same height as your arms so the force acts in a straight line. Elasticity and stretching depends on force and the tension in the cord. What we want to work out is how to produce as much tension as possible in a cord which is fixed at one end and has a constant force on the other in between any forces can be imposed but they must not be so strong as to override the one fixed force at the end (your pulling power). Could be one for a physics forum if there is such a thing, dont have to mention what you are up to! It may be over people’s heads but it would be nice to have a full vector diagram with all forces and tensions shown.

Vector math is not like regular (scalar) math. The directions involved determine the outcome. 1 + 1 can = anything from 0 to 2 depending on the directional interactions. I teach this stuff every semester in physics. It is commonly covered in engineering….suspension bridges, etc.. That is why telephone and power wires are hung in large parabolic loops and not tight and horizontal. They would break under their own weight if hung tight because of the 180 degree angle involved. (and because of shrinkage in cold weather) Pull on a tight horizontal (180 degree) line and the tension within the line is increased greatly as you pull in the center. tensile tension increases geometrically as the angles of support increase from zero to 180 degrees. Classical physics. MXL (7-up)

MagnumXL- Thanks for that. I have been reading more but haven’t found any good force diagrams yet. What you say makes perfect sense and I wonder if there is a better way of introducing forces, maybe one up and one down along the shaft? I find the A-stretch over the hand is great, maybe even better than the V stretch. With the A stretch you are using a sort of parabolic loop so do you think it could be better? I could barely do A stretches a few weeks ago, now I can easily get my hands in position, must have got some extra length :-) one week till measuring time and looking good! I think traction on the arm may be a factor too, I tied a 2.5kg plate to some rubber tube and was messing about trying to lengthen it by placing forces on it in different areas. I was able to get more stretch but the rubber was gripping onto my arm so I was unsure if the test was really equivalent, then I thought the same may happen with my own arm. I have done underleg stretching with a condom and could get good grip all along the shaft, just wash the condom in detergent to get all the lube off it.