[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 550
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This is correct. But the body must still be brought out of this position from the vertical.
Now came the excuses.
There is only one way to do this - to push off the ground, i.e. to exert force 5 on the ground and receive force 7 in response, which will move the centre of mass forward.
Don't you really understand? Walking begins by shifting the point of contact, i.e. axis, to create misalignment and force (1).
alsu:
Well, the horizontal component of the reaction force F7 = mg*sin(a)*cos(a) is not balanced by anything, and therefore simply acts on the body until the angle a equals 90 degrees (sin(a)*cos(a)=0), i.e. until the complete fall.
In perfect agreement with this deduction, after falling, the centre of mass of the body is below and to the left of its original position.
Don't you really understand? Walking begins by shifting the point of contact, i.e. the axis, to create misalignment and force (1).
It is impossible to displace something without an external force acting on it. And there is only one force - the reaction of the support to our effort.
By the way, there were no excuses. Gravity is not a useful force in walking, although energy has to be spent on overcoming it at every step.
Another example is walking up a steep hill. Does gravity pull us up as well?
Don't you really understand? Walking begins by shifting the point of contact, i.e. the axis, to create misalignment and force (1).
It is impossible to move something without an external force acting on it. And there is only one force - the reaction of the support to our effort.
Oh, man... I don't even know how to explain it. If a person wants to walk forward, they lift the toes of their feet, thereby shifting their fulcrum and getting force (1).
Gravity is not a useful force in walking.
Yeah, not involved at all. If the Japanese thought that way, there would be no ashimo yet.
Another example is walking up a steep hill. Does gravity pull us upwards as well?
An example of what?
Anyway, if you don't understand such elementary things, I don't know how to explain. I'm not a good teacher.
So. the force of gravity is applied to the centre of mass.
(2) is the projection onto the axis
(3) -- the transfer (2) to the point of contact with the surface.
(4) -- the projection of (3) onto the vertical axis, balanced by (6) the opposing force of the support
(5) -- projection (3) onto the horizontal axis, balanced by (7) the rest-friction force
(1) -- this is the force that drives the walking motion.
(6) and (7) are simply counteracting forces. Derivatives, eh)))
You'd better not start.
All right, I won't. Otherwise, I can show you a picture, both static and dynamic, and I can show you graphs of power over time.
Don't do it, don't do it.
Gravity is not involved as a useful force in walking, although energy has to be expended to overcome it in every step.
Yep, not involved at all. If the Japanese thought that way, there would still be no asimo.
An example of what?
Anyway, if you don't understand such elementary things, I don't know how to explain. I'm not a good teacher.
Here I disagree with you. We do fall down at every step, then rise up and fall down again and again. This is the peculiarity of the stepping mechanism. You can compare it to the 'optimality' of the wheel for as long as you like, it is indeed optimal, but only if there is a more or less level road. And since living creatures came before the Roman Empire, they step and jump, some crawl:)
"Not involved as a useful force" - "Useful" in this context means "helping to move". We, on the other hand, need to overcome the force of gravity - it makes the body fall, we, on the other hand, put our foot up and raise the body to its original height, i.e. work against mg.
If we simply glide with our feet on the surface, gravity can be excluded from consideration altogether.