In Figure 4 a the car is flat on the road. In Figure 4 b the car is tilted but because the vertical line through the centre of gravity is inside the case of the car and so the car falls back to the level again. But in Figure 4 c the vertical line from the centre of gravity falls outside the base and so the car topples over. The effect of size of the base is shown by the three stools in Figure 5. That means that the vector of angular momentum has its back on the ground, at the point that the tip of the top touches the ground, and its head is performing a circle on a plane that is parallel to the ground.
That motion is the precession of the spinning top. Finally, I think that the reason for assuming a much faster rotation than precession for the top, is to simplify the calculations and consider the top as a gyroscope. The angular momentum has to be conservate: i. As cedric said, the gravity, works for the axis of the spinng mass to fall horizontally on the plane: if this happens also the angular momentum as to torque!
Then u can consider that the magnitude of the angular momentum is proportional to the spinning speed: so as the spinning velocity gets higher it gets, for lack of a better word, "easier" for the top to resist the gravity.. If u try to spin a top on an inclined plane you will need to spin it faster to obtain the same "resistance to gravity"! From your linked article :. Spin a top on a flat surface, and you will see its top end slowly revolve about the vertical direction, a process called precession.
As the spin of the top slows, you will see this precession get faster and faster. It then begins to bob up and down as it precesses, and finally falls over. The drawing shows a circle instead of a spiral due to leaving out variables like friction and gravity. The quick answer is that, for the top to fall over due to gravity, each fragment of the top that is moving around the spin axis has to change its individual direction of movement.
They are already changing direction around the spin axis, due the rigidity of the top keeping them moving in a circle. And as it slows down, the effect of gravity has more effect, and it falls over. This is a nice example which shows understanding does not come automatically after completing a calculation. But calculation still serves the perhaps the most important guide. I think these discussions have already elucidated the issue.
Unfortunately, they proceeded using Euler angles. I have reformulated their discussions here. Hope that helps. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
Create a free Team What is Teams? Learn more. Why don't spinning tops fall over? Ask Question. Asked 10 years, 11 months ago. Active 5 months ago. Viewed 17k times. Improve this question. There's an important result from all of this - you get slower precession if the spin is fast or if the couple is small. This is because the smaller the couple, or the larger the spin angular momentum then the change in spin direction red arrow is smaller. The moon, for example, goes around the Earth at constant speed, but its' direction of travel is changing continuously due to the force of the Earth's gravity.
See other gyro links here. Explanation B less technical : What stops a spinning top from falling over? All we need to show is that the force of gravity is insufficient to cause the top to fall. The only force acting to push the top over is gravity. First think what happens when the top is not spinning. It falls over and we get a feel for how long it takes for the top to fall and how fast it is going when it falls. This gives us a feel for how much angular motion that gravity alone can give to the top if it were to fall over.
Let's call this angular motion "spin", but note that gravity can only create "spin" about a horizontal axis. In fact even with the windows closed, a strong gust of wind can affect the pressure inside due to the elasticity of the glass.
A gust of wind or an earthquake is enough to break an object from a position of stable mechanical equilibrium in just one blow, but what about when there is no apparent reason and no obvious vibration? You may not think that vibrations can cause an object to fall but this can be a slow process. This is why these objects fall after being left on a shelf or table top for days, weeks or even months. The object doesn't appear to move but it is, just very slow and then at some point the object's centre of gravity changes and it falls over.
Every time you switch your washing machine on the vibrations could be slowly edging an object in the house slightly closer to tipping point, until one day, it falls. The most common way an object can be effected by these kind of vibrations is your own movement through the house, especially if you have wooden floors.
Each time you walk through a room you create vibrations, opening or closing doors could also be a cause, as could banging on a wall. Photo: pixabay. A good example of this is if you have a small toy or piece of stationary on a desk, also on the desk is a speaker which is playing loud music. The vibration from the speaker can cause the object to inch closer to the edge of the desk by a fraction of a millimetre at a time, eventually it'll fall off the desk.
A change in air pressure can also cause something to fall off of a desk. Let's say you've put a book down on a desk in a rush, half the book is on the desk, the other half is hanging over the edge but it's balanced and stable.
It could stay like this for days, but if you've happened to balance it in just the right way and suddenly there's a change in air pressure then that book's balancing point might change and it falls. Another factor which can make something fall is gravity and how gravity effects an object as it changes state.
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