This time 3 questions at a more basic level, but no less interesting
Does centrifugal force exist? If not, what is that imaginary force we feel?
There is no such power. In general it can be said that the centrifugal force is a by-product of acceleration and not its cause. However, everyone feels this force when turning the car. It is the force of inertia that causes us to move in a straight line outside the circle of motion. The centripetal force pulls us inward. To illustrate the difference between normal force and centrifugal force, let's imagine that we are the object rotated by a rope. The forces in the system are the inertia that pushes you out of the circle in a straight line, the force of the rope pulls you in, and the combination of both creates (by vectorial connection of perpendicular components) a circle. But there is no force pulling you out of the circle, in a direction opposite to the direction of the rope's pull. In fact, it can be said that the rope makes you accelerate but in a different direction than the direction it pulls, and this is as a result of connecting speeds. Another example of this can be seen if we shot ourselves from a cannon. We accelerate towards the center of the center, but we move diagonally down and not directly vertically.
Why does a bicycle fall while standing and does not fall if we drive it fast?
When we ride a bicycle we create a rotational velocity with a vector that faces (according to the right-hand law) to our left side. We have created angular momentum, a constant factor in the universe, and on the basis of its conservation we will prove that the bicycle will deviate in the appropriate direction in the event of a fall. Suppose the bike wants to fall to the left. Now the force exerted by the floor (on the wheel tilted at an angle to the left) creates a vectored torque in the backward direction of the bicycle (again, using the right-hand rule). The force is the normal, the arm is the distance between the wheel touching the ground and the center of mass of the bike. To illustrate, every child knows that the center of gravity of the body cannot be brought beyond the tip of the nail, because beyond this point we will fall. In the case of the bicycle, the balance will be to the left and back. To offset the added component (since we determined that the momentum must be kept constant) the bicycle is shifted to the left. Now again the only component of the rotary motion is our new left.
If a locomotive exerts a force equal to what a trailer exerts on it, why do they move?
Newton's third law states that if a force is applied to a body, the body resists with a force equal in magnitude and opposite in direction. If both exert equal forces, shouldn't they stand still? The basic question that should be asked is what is the axis system we are using. If we place the axle system on the train, then there are two forces: the engine's force and the train's pulling force. For a system placed on the car there is only the pulling force of the train. The difference is in the external forces in all systems. The engine should be seen as an external force acting on the train (let's say it has the same mass as the car M ) and not as one that pulls the car. The motor force (F) moves 2m with a constant acceleration a. Since the train is moving with acceleration a, the force pulling on the train is Ma . So it is true that the forces exerted by the train and the wagon offset each other, but twice as much force is exerted on the train. If we move to our lives, in the case of people pushing each other in line at the bank, we can refer to the differences between the friction that their feet exert on the floor. And if the friction that the second exerts on the floor is the same in magnitude as the friction that the first exerts on the floor - then yes, they won't move until tomorrow. All the difference is in the external forces - an engine, friction with the floor, a hand holding something. For example, in handshakes, the winner is the martyrthat does not competeIn the hand pull itself, pull the handle on the side of the table the hardest. sounds strange? We can see the two competitors as one system. This system has only two external forces: the 2 hands that hold handles (we will neglect friction with the floor, or rather we will include its contribution to the force of the other hand). If these forces are equal (and the hands of the competitors are equal in length) the competitors will remain in a static negotiation. If force A is greater than force B, then force B will not be able to prevent the system from moving, the sum of the torques will be different from zero, and the whole system will twist in the direction that force A drives it. Of course, we can fight without hands, and then the one who exerts a greater force with his shoes on the floor will win. The bottom line is simple: when you apply a twist to the opponent's arm, your body must twist in the other direction, in a way that offsets the appearance of angular momentum. We can see this phenomenon in the swing. When a child rocks himself forward, an angular momentum vector is created that faces to the right (according to the right-hand law). But a chain is not like a shoe that touches the floor, i.e. stable and able to apply torque or force. A chain can only exert a vertical force. Therefore, the child who "throws" his legs forward will always feel his head moving back, and thus the angular momentum in the universe is preserved.
8 תגובות
explanation:
If the pressure (!!) is higher during boiling, the amount of heat invested will be smaller to cause vaporization. Of course the temp will be higher because the pressure (!!) is higher.
I won't comment on the first argument, because if that's what you studied at the Technion, then you probably didn't listen.
I never said that water boils in the Dead Sea at a temperature lower than XNUMX degrees, which only proves that your ability to understand is even lower than your ability to listen. I was talking about pressure and amount of heat invested. And by the way, I received two correct responses to the email that the fact I mentioned is taught in the first year in the first semester at the university, and indeed it is true. Maybe you should visit such an institution sometime, who knows, maybe you'll learn something.
The reason I answer in this way is because you are tired of me, the people who don't really understand, but insist over and over again to show how smart they are. Open a thermodynamics book for first year students, and read what a bell curve is. First year, second class at the university. As the pressure increases, the heat of evaporation decreases. I don't believe I have to define what a bell curve is to educated people. Shame on you, fool and the people of the land.
Apart from the clumsy wording and gross mistakes in other news as well, in this article you are exaggerating and perpetuating a common mistake, which in every first year physics course at the Technion once again proves its absurdity:
The balance of weight on a bike has very little to do with angular momentum. In fact, we maintain balance because turning the steering wheel (the "handlebar" in popular parlance) shifts the weight of our gravity so that it passes from right to left to the line connecting our points of contact with the ground, and thus we can "fall in a controlled manner" to the right or left. There are two ways to disentangle the connection between bicycles and angular momentum: one of them involves calculating or estimating the mass of the wheel (negligible relative to the mass of the rider and the bicycle) and showing that there is not enough mass to explain the weight balance, at reasonable speeds. The second method is more fun: in snow bikes, each of the bike's wheels is replaced by a short ski skate. Anyone who knows how to ride a bike, immediately knows how to maintain balance even on a snow bike. There is no angular momentum because there is no rotation. parable.
Much more can be written about errors in other information by the same writer, for example about the fact that water on the shore of the Dead Sea boils at a temperature higher than 100C, not lower. Not suitable for the level of the "Hidan" site. It took me a while to like this site about my offspring, and it's a shame that nonsense creeps into it as well.
Reply to "engineer"
You messed up and you were wrong.
Hints:
1. Decide what the purpose of your claim is.
2. Your response can be summarized in only one section!!!
3. There are two options here:
- You don't know how to articulate.
– You articulate poorly.
After all, I invite the readers, as I have done in the past, to send me questions with detailed answers and I will publish everything that is correct and interesting. As for the Hebrew issue, I agree with you, it is difficult for me to convey my logic to the reporter and I write clumsily and clumsily. My Hebrew is not good at all, and because I think in a mess, my writing also comes out like that. Regarding the correctness of the things... let's say that no commenters have yet appeared who dazzled my eyes with spectacular physical insights. My critics, perhaps because of my low level of writing, attack clarity more and I certainly promise to try harder if I am given it. Besides, I also write absolute nonsense about Newton's laws and it provokes a fruitful debate - we all benefited. I have a lot to learn and I make more mistakes than most people.
I'm not comfortable saying - but Yonatan's explanations are cumbersome (including the Hebrew) and, therefore, difficult to learn from them. And on the assumption that they are correct, if it is possible to simplify them - all the better.
And the scripture refers only to the articles of this day (hint - April XNUMXst...).
I would appreciate it if you would wait for us with my mistake. Please also specify mathematically.
In connection with the problem of the locomotive and the train.
You messed up and you were wrong.
Hints:
1. The solution is simple in simplicity.
2. For the solution it is sufficient to use Newton's third law only!!!
3. There are two options here:
– You are not an engineer.
– You are a bad engineer.