Engineer Garin's Paraboloid - page 21
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The algorithm has been rewritten hundreds of times and is available online in countless numbers and variants, completely free of charge. But some people don't realise this.
and that's for sure.2 alsu We are considering the motion of a body under the influence of forces - there are other sections behind Kinematics ;). That's what I'm saying - there are a lot of simplifications in the initial stages, which are still difficult to understand at school. Friction force is a derived force, i.e. it is a reaction force that occurs in the presence of an external force and in the opposite direction to the action of the external force. In the cases you have drawn, the friction force arises as a compensation, i.e. there must also be a force that causes the friction force to arise - this is the first
Why would there be such a thing? When you walk on the ground, you benefit from the resting friction force, which arises as a reaction to your internal muscular tension. The friction force is forward, it's what moves you. Or do you think there's some mythical external force that magically carries you?
Similarly, when you turn the car, the resting friction force arises as a result of the car's wheels (and indirectly the driver's hands that turn the steering wheel) acting on the road. That is, it is a reaction to internal processes occurring in the material body. Engines (internal combustion engine, legs, etc.) serve for this purpose - to cause interaction with the external environment, leading to movement of the system due to the internal process.
Vladislav, take the trouble to write down Newton's second law at least once, it will not take away from you. Here is a specific question, think about it: if the frictional force is balanced by your centrifugal force, then where the hell does acceleration come from? And don't say that forces are applied at different points, for 1 Law it doesn't matter - "if no forces act on the body, or their action is compensated, then the body is at rest or in uniform rectilinear motion". (or maybe 1 law has some "unschooling" interpretations too?)
and second: about the example with the cube: the tilting moment arises relative to the contact point, not relative to the centre of mass, i.e. relative to the line of friction force, and it cannot create a moment there - the shoulder is zero
The tilting moment always arises and is considered relative to the centre of mass. Try to picture a cube with a force applied horizontally to the centre of mass with no friction at the point of contact - it won't tip over anywhere, it will just slide.
On reflection: here you put another cube on the cube - one more point of contact is formed. Which of the two and why will you choose to calculate the moments? The correct answer is none. In any mechanical system there is only one dedicated point, the point of the centre of mass. Otherwise confusion and collapse of science.
If in doubt, imagine a flexible rod instead of a cube: when it rotates - moving along a curvilinear path - it will bend along the curve but in the opposite direction to which it should under the influence of the frictional moment you drew: the upper edge will move away from the centre than the lower and the deflection will be inwards. According to your drawing it should be the other way round - deflection outwards.
And what about the friction forces in the rope? ;) .....
Are you referring to the rotation of the body on the rope? Absolutely the same situation. There is one single force acting on the ball (enough with the cubes) - the tension force of the rope, directed exactly to the centre of rotation. The acceleration is also directed there.
Another example is the movement of the planet around the sun. (simplified - in a circle). The only force acting on the planet is the force of gravity. It also causes centripetal acceleration directed precisely towards the sun. If the gravity of the sun was balanced by something, the system would collapse.
In short, Vladislav, if you wish still to argue, you are welcome with your version of drawing with the applied forces, moments and writing 2 MN: the equilibrium force = mass*acceleration, only in such form, and no more. You asked your opponents to draw it - they drew it for you. Do you think it is wrong? Then argue on the merits, and don't try to be silent.
Really? Can you throw me a link? I've had enough of "a hundred times" and "untold numbers".
In short, Vladislav, if you wish still to argue, welcome with your version of figure with the applied forces, moments and notation 2 MN: equilibrium_forces = mass*acceleration, only in such form, and no more. You asked your opponents to draw it - they drew it for you. Do you think it is wrong? Then argue on the merits, and don't try to be silent.
To follow up, I quote https://ru.wikipedia.org/wiki/%D0%A1%D0%B8%D0%BB%D0%B0_%D0%B8%D0%BD%D0%B5%D1%80%D1%86%D0%B8%D0%B8
Force of inertia (also inertial force) is a term widely used in various meanings in the exact sciences, as well as in philosophy, history, journalism and fiction.
In the exact sciences, the force of inertia is usually a concept,which is used for convenience when considering the motion of material bodies in a non-inertial frame of reference[1]. Particular cases of this force of inertia are the centrifugal force and the Coriolis force. Besides, force of inertia is applied for formal possibility to write down the equations of dynamics as simpler equations of statics(kinetostatics, based on principle D'Alamber)[2].
Why would you do that? When you walk on the ground, you use the resting friction force, which occurs as a reaction to your internal muscular tension. The force of friction is directed forward, it's what moves you. Or do you think there's some external mythical force that magically carries you?
Friction can't propel anybody forward. It doesn't move you off the ground -- it keeps your feet from sliding. It's the deflection of the centre of mass from the vertical axis of equilibrium that moves you.
The error in reasoning is the same as in the case of centripetal force.
Why would you do that? When you walk on the ground, you are using the resting friction force, which occurs as a reaction to your internal muscular tension. The force of friction is directed forward, it's what moves you. Or do you think there's some mythical external force that magically carries you?
Incorrect - the movement is possible in the presence of reactive force, which is transmitted through the feet to the support due to muscular tension. The presence of frictional force prevents slippage and enables movement.
Similarly, when you turn the car, the resting friction force arises as a result of the car's wheels (and indirectly the driver's hands that turn the steering wheel) acting on the road. That is, it is a reaction to internal processes occurring in the material body. Engines (internal combustion engine, legs, etc.) serve for this purpose - to cause interaction with the external environment, leading to movement of the system due to the internal process.
Vladislav, take the trouble to write down Newton's second law at least once, it will not take away from you. Here is a specific question, think about it: if the frictional force is balanced by your centrifugal force, then where the hell does acceleration come from? And don't say that forces are applied at different points, for 1 Law it doesn't matter - "if no forces act on the body, or their action is compensated, then the body is at rest or in uniform rectilinear motion". (or maybe 1 law has some 'unschooling' interpretation too?)
Acceleration is taken from an external force: without an EXTERNAL force, the body will move straight and uniformly.
The tipping moment always arises and is considered relative to the centre of mass. Try picturing a cube with a force applied horizontally to the centre of mass with no friction at the point of contact - it won't tip anywhere, it will just slide.
This is nonsense - a tilting moment can arise around any point. In a crane, for example, it arises relative to the tilted arms. If the torque is not compensated for by the reaction force or weight, the body will start to rotate around the point relative to which the torque occurs. Have you even studied theoretical mechanics at all ??????????
On reflection: here you put another cube on the cube - another point of contact is formed. Which of the two and why choose to calculate the moments? The correct answer is none. In any mechanical system there is only one dedicated point, the point of the centre of mass. Otherwise confusion and collapse of science.
I don't think you understand the situation at all. The rod will only bend inwards if it is tied to the centre of the circle by the middle. Think about it and you will see that in your example the rod is bending outwards. In perfect harmony with all the forces and moments at work.No, by deflecting inwards, you can rotate the flexible rod.
Are you referring to the rotation of a body on a rope? Absolutely the same situation. There is only one force acting on the ball (enough with the cubes) - the tension force of the rope, directed exactly to the centre of rotation. The acceleration is also directed there.
No, wrong.
Once again - under the action of a force, the body begins to move along the line of action of the force . If there is only one force applied and it also acts towards the centre of rotation, the body must move along the line of action of the force, i.e. towards the centre of rotation or will you also argue that when a ball on a rope rotates, it tends to fall towards the centre of rotation and the rope prevents it from doing so ))))))))))))) ??????? What is the force that STRENGTHENS the rope? Or are you going to argue that the centripetal force acting towards the centre of rotation does not compress the rope, but pulls it taut? Or would you also say that the rope is not under the action of a tensile force?
Another example is the movement of the planet around the sun. (simplified - in a circle). The only force acting on the planet is the force of gravity. It also causes centripetal acceleration directed precisely towards the sun. If the gravity of the sun was balanced by something, the system would collapse.
Why doesn't the planet fall on the centre of rotation (see previous comment) ? what keeps it on a circular trajectory ?
In short, Vladislav, if you wish still to argue, you are welcome with your version of drawing with the applied forces, moments and writing 2 MN: the equilibrium force = mass*acceleration, only in such form, and no more. You have asked your opponents to draw - they have drawn it for you. Do you think it is wrong? Then argue on the merits, and don't try to be silly.
Apart from VIKI do you have a basic education in mechanics ? Well, have you at least studied theoretical mechanics?
BOOA_GA_GA . the worms in Newton's coffin must be turning over five times a day.
there is no gravity. inertia is wrong. centrifugal force is nonsense. everyone here has a physics degree with a philosophical bias))))
erase everything you've learned and create new sciences)))))))
Figure of forces and Newton's 2nd law to it, without that there is nothing to discuss.
https://ru.wikipedia.org/wiki/%D0%93%D0%B5%D0%BE%D1%81%D1%82%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B0%D1%80%D0%BD%D0%B0%D1%8F_%D0%BE%D1%80%D0%B1%D0%B8%D1%82%D0%B0#.D0.92.D1.8B.D1.87.D0.B8.D1.81.D0.BB.D0.B5.D0.BD.D0.B8.D0.B5_.D0.BF.D0.B0.D1.80.D0.B0.D0.BC.D0.B5.D1.82.D1.80.D0.BE.D0.B2_.D0.B3.D0.B5.D0.BE.D1.81.D1.82.D0.B0.D1.86.D0.B8.D0.BE.D0.BD.D0.B0.D1.80.D0.BD.D0.BE.D0.B9_.D0.BE.D1.80.D0.B1.D0.B8.D1.82.D1.8B
Tired of it - Study something beyond primary schools knowledge.
Especially for the "C" students I cite paragraph 19 from the physics textbook for the 9th grade (which completely repeats everything I have said). I suggest that you carefully and to the end reread, think over and then argue with the authors of the textbook (Peryshkin, Gutnik, 2009). If necessary, I can cite five more textbooks - school, university or whatever you want.
Vladislav, I especially advise you as a mechanic: close the gaps in the school course. Then take up your institute textbooks, and reread them too (I assure you, it says the same thing). And in general, I think something to forget from the school course - not a shame, it happens to all. The difference between professionals is that they are capable of self-criticism. But if a man believes that only one can access the truth, just because his credits contain the phrase "theorem-mechanics" (which he obviously studied rubbish), and all the rest, including dozens of authors of textbooks - morons, then from such "specialist" nothing but public danger can not be expected.
In favour of absence of self-criticism at you speaks also that you call my statements nonsense, without giving thus any arguments, the most lucid from which, I repeat, will be the drawing of forces acting on a body with writing down of the corresponding equation. But since (it's obvious to me, I've studied physics) you'll never draw such a picture, simply because of illiteracy of your ideas, the next post you'll probably just tell me to f*** off.
TheExpert, deflection from the centre of gravity is impossible without the force of rest friction. It is what we use to propel ourselves forward when walking, and it is the only force acting on a person from the external environment in the walking direction. The force of gravity is significantly used (it is the pulling force that causes the friction force), but it acts downwards and thus does not do any useful work. In addition, it is completely balanced by the support reaction force.