[Archive!] Pure mathematics, physics, chemistry, etc.: brain-training problems not related to trade in any way - page 66
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Mischek, I made a mistake. Of course, the system is non-inertial.
I think it's too much. I didn't order this much music.
Do I strike you as a megalomaniac?
Hmm... I'll see a psychiatrist ... :-(
Пожалуй это слишком. Столько музыки я не заказывал.
"Resident: Who?
Brigadier: I have people. Orchestra. Fifteen men of living men. They can kill, stab anyone who won't bear it now. Mania, please.
Fat Mania, in socks and men's boots, struck the plates and looked at her watch.
Tenant: Just a minute, who sent you here?
Brigadier: How should I know? Maybe you did. What, am I supposed to remember everyone?
An enraged Trombone bursts out of the group.
Trombone: Misha, will there be anything, or we'll blow this halaboose in half. I'm an invalid, you know.
Brigadier: Zhora, don't torment yourself. People have a lot of grief, they want to bargain. Name your price, we'll talk like cultured people. You haven't heard our sound yet.
Tenant: I can imagine.
Brigadier: Just a second. You hear what we sound like, you'll take off your shirt. These people feel other people's grief as if it were their own.
Resident: I can well imagine.
Brigadier: Stand over there and listen here. Aunt Manya, please give the signal for formation. Fat Mania struck the plates and looked at her watch.
Brigadier (strode in cavalry step): Konstantin, button up, hide your cheeky tattoo with those illiterate expressions. You write something new all the time. If you don't take it out, I'll suspend you from work. Fyodor Grigoryevich, you may be a conservatory student, you may even be more cultured than we are - you know the notes, but this cowboy is humiliating you. We have work, thank God - the street movement is growing. We saw off fifteen people in July alone.
Now you, Mania. I don't care what you cook for lunch, but you smell like fried fish every day. Switch to vegetables or we'll say goodbye. A sad signal, please.
(The orchestra plays a fantasy, which can hardly be distinguished from a funeral march).
Resident (applauding): Thank you very much, that's enough. But it's all in vain. Someone must have made a joke.
Brigadier: Maybe, but it's none of our business. I've taken fifteen people off the job. I don't let a young man finish the conservatory. Madam Zborowska threw the farm on a young thug to keep him healthy. So you want me to understand jokes? Pay up, then we'll all laugh together.
An enraged Trombone comes out of the group of musicians.
Trombone: Misha, why are you messing with him? Let's kick him in the head and play our own game.
Brigadier: Zhora, don't be so hard on yourself. You haven't served time for that case yet, why are you nervous again?"
(c) M.M.G.
The force of inertia ? I don't know such a thing. But if you listen to what VladislavVG says, you can understand it in principle. But it is still, to be more precise, not a force of inertia, but simply the net result of forces applied to a material point.
Centrifugal force? Well, that's a fiction that arises when you move to a non-inertial reference frame. There is one force - centripetal.
Thank you, Alexei. You've restored my faith in humanity.
By the way, about the mirrors.
The condition of the problem does not say anything about the placement of these mirrors, their number and so on. You can hardly give an answer in such a situation.
If it's about mirrors to cover the walls, then I'll support Richie, the lightness in the room will increase, you can even calculate how.
If the mirrors are just placed randomly in the room, you'd be right too.
The approach is simple. A light bulb emits light. It's energy. The level of light is one way of measuring it at a given point. On the other hand, all the surfaces in the room reflect that energy partly, partly absorb it. If the energy the bulb emits per unit of time is greater than the energy it absorbs, the amount of energy in the room increases and so does the illuminance. But this only lasts until a dynamic equilibrium is established between emission and absorption.
Now we cover the walls with mirrors. As Richie wrote , their reflection coefficient = 95%. This means that in order for the energy of the emitted light wave to be reduced by a factor of 10, it has to be reflected 45 times from the mirrored walls. It's not difficult to calculate the time it would take for this to happen. It's clear that during this time a light bulb, which radiates continuously, would add a considerable amount of light energy to the room. So the mirrors would for some time upset the balance of absorption and emission, leading to more illumination.
2 Richie: Your reasoning in the problem about the light bulb and mirrors would be correct, if the source of light (real) and its image in the mirror were independent. Are you familiar with the calculations in wave theory of light, at least superficially? I think that if these calculations were performed by a program simulating the light source in the mirror, the Intel processor would be broken by now.
Here's a simple little experiment that you can do now too, if it's dark outside your window. If your window panes are clear (which I don't doubt) and the curtains aren't closed, they reflect another source of light - the main light bulb in the room, i.e. the one in the chandelier. Mine is definitely reflected. Close the curtains now. Is the room getting darker?
Mathemat, you have me completely confused.
So, there's a room. There's a window in it. There's a chandelier. The chandelier is actually reflected in the window. Why is it reflected? Because the light doesn't go all the way outside, let's say 1% of it is reflected back into the room. I close the curtain. It's light beige. The room gets lighter. Why? Because the light reflected from the window is no longer 1% (open window - without a curtain) but more than 40%.
But what's a mirror got to do with it? A mirror is a highly reflective surface that reflects more than 98% of the light incident on it. A window is a black hole for light.
I am not claiming that a mirror increases the total luminous flux emitted by a lamp. Installing mirrors allows you to increase the light by increasing the proportion of the light flux reflected from the walls. It appears that you are disagreeing with me and disagreeing with the results of the programme.
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Let's move a little bit away from the condition of the problem.
Imagine a room with black walls and the same room with white walls. The rooms are the same. The light fixtures are the same too. The question is: which one is brighter?
Mischek, Ответ на вопрос о электрическом радиаторе:
Станет ли он греть лучше? Да, станет. И вот почему. Сопротивление спирали радиатора зависит от их температуры. Чем сильнее конвекция, т.е. чем сильнее воздушный поток направленный на радиатор, тем ниже температура спирали (хотя, она ниже незначительно). А это значит, что по закону Ома ток протекающий в цепи спирали будет выше. Выше ток - больше потребляемая и выделяемая мощность. Вот и получается, что если около нерегулируемого электрического радиатора поставить вентилятор, то тепла он давать будет больше.
Aren't you confused with a thermistor?
Show how the resistance of the heating element depends on the temperature
About the plane: if we accept a model that is more or less close to reality, the plane cannot take off in a normal way according to the definition of the problem. If the transporter breaks, it will take off, if the wheels are worn out, it will fall, but this is outside the scope of the original formulation. Normal take-off is prevented by the force acting on the wheel of the undercarriage by the transporter at the coupling point. It is clear that transporter surface will move with such acceleration to compensate shift in plane- landing gear-wheel system. This is how I understood the problem statement. maybe I did not read it quite carefully.
PS. In case anyone didn't get it, the landing gear wheel has mass-inertia.
PPS. Yurich, did you draw the diagram yourself?
People, let's post problems that are unambiguous in their answers.
We have different opinions about two times two, and if we make up our own problems...
Aren't you confused with a thermistor?
Show me how the resistance of the heating element depends on the temperature.
No, I'm not. Are you surprised that the resistance of the nichrome is a function of temperature? Unscrew the bulb from the chandelier. Measure its resistance and relate it to the power of the bulb. It will turn out that the resistance of tungsten filament at 20 degrees C is 10-15 times less than its resistance when it is burning (about 2500 degrees).
Here are temperature coefficients for some alloys and metals: http://www.calc.ru/606.html
Нет не путаю. Вас удивляет то, что сопротивление нихрома зависит от температуры? Выкрутите из люсты лампочку. Померьте её сопротивление и соотнесите его с мощностью лампочки. Окажется, что сопротивление вольфрамовой спирали при температуре 20 гр.С раз в 10-15 меньiе, чем её сопротивление при её горении (около 2500 град.).
Вот вам температурные коэффициенты для некоторых сплавов и металлов: http://www.calc.ru/606.html
I don't need a link.
Show here how the resistance of the heating element in your electric radiator depends on temperature