Recent content by danlightbulb

Thanks for the replies everyone. If I may continue. I understand now that an astronaut traveling towards the moon is under the influence of gravity but he can't actually 'feel' the gravity because him and the rocket are traveling at the same velocity. And I can see now that it would be the same...

Hi all, This isn't a homework question, its just something I'm personally wondering about. I understand why an astronaut in orbit around the Earth feels weightless, because he is in a constant state of freefall, traveling towards the Earth just as fast as the Earth is dropping away underneath...

Guys I am struggling to believe there isn't a mathematical solution to this problem. There are surely enough known constraints to be able to work this out, for example: 1. The load can only travel vertically. Therefore the angle at A1 cannot get smaller on its own because L1 length is fixed. If...

Hmm i think in theory yes, many angles can fit the solution, but for a given individual for given limb lengths he only squats with one particular set of angles. So what is it that is making those angles what they are for a given individual? There are possibly more contraints that can be given...

So in the human body, what stiffness does a joint have then? Its actually a range of none to lots, and that notional stiffnes is created by the muscles during the movement. If I squat 50kg the angles are the same as if I squat 100kg, so I gather the muscles create a kind of dynamic stiffness to...

Just the lengths are known because you would be measuring the limb lengths of people. The angles are controlled by the pull of the muscles around the joints, and are different for every person because limb proportions are different for everyone. However in this position the load is static, so...

Yes I can see that, but we don't know the value of A3 in the first place so how can we numerically calculate A3 just knowing L3, even if it is a right angled triangle. We still only know the numerical value of length L3 unless I am missing something? Using my previous numbers, L5=0.2m, L4=0.02m...

I can see that B3 = A5 yes, but how does that help figure out A3? Im still not really sure on the right angled triangles. Are you saying that one of them might be if a line is dropped from the knee joint vertically down to the horizontal line above the foot? In that case L3 is the hypotenuse...

Like this: Ive labeled the angles between the horizontal lines as B1, B2 and B3. Still don't understand what A3-A5 means.

Im not sure what you mean sorry. Are you saying A3 minus A5 there? Or A3 to A5? A5 is the angle you labelled, I assumed it was the angle between the floor and the foot (L5) is that right? I don't see how anything there can be a right angled triangle.

You mean by subdividing them? I did think of that, but didn't know where to start with it.

You've picked the only right angled triangle there haven't you lol. So you're working out what A5 is (a new label representing the angle between the toe end of the foot and the ground), by taking the inverse sine of opposite (L4) / hypotenuse (L5), which only works for this bit because its a...

Yes it would because I really don't think I can solve it myself.

I was simplifying. The muscles are under tension and the bones under compression in a static position with the load stationary. Forces in the muscles equal and opposite to the forces in the bones, and around the joints, there are moments which are equal and opposite also, again because the load...

Hi thanks for the replies. The forum mods asked me to mention that this isn't a homework problem - I am not a student. Its just something I am trying to figure out for myself. Regarding attempts at solving it. I know basic trigonomentry and how to use sine, cosine & tangent. But they aren't...