Pure maths, physics, logic (braingames.ru): non-trade-related brain games - page 117

[Sceptic Philozoff]

muallch:
It has been argued that by throwing the mass out perpendicular to the cart, it can be slowed down that way, right? "The speeds of both carts may not change at all" - what does "may not change" mean here in relation to my example? Can and do? Alexey, please explain this point. Exactly for my two carts.

To slow down is to reduce the speed.

And you can reduce the momentum in a different way - just by ripping off a piece at the same speed. The speed will not change, but the momentum will drop.

DmitriyN:

If snow falls on a cart, it means that part of the kinetic energy of the cart is transferred to the snow that fell on it. If that snow, which has energy, is thrown out of the cart, then the cart's energy is reduced. The weight of the cart remains the same. So, the speed should drop faster than the other cart. Alexey, is it so or not?

Not exactly. The friction is different - more than a cart that's not throwing snow. It's heavier.

[Dmitry Fedoseev]

DmitriyN:

Fan video. This is my first time shooting with a new camera, first time working with youtube and first time working with a video converter, so please don't shout too much about the poor quality. On the technical side, it's not perpetual motion, but just one of the effects of physics and unconventional use of radio components. I will try to upload better quality later. I didn't solder it, so I don't know exactly how and what works there. You can use a smaller capacitor and build it inside, but the fan will rotate slower. The LEDs at the fan are off, with them it doesn't work at all. Without air (Alexey asked) the fan cannot work.

From 1:40 onwards, something about it starts spinning on its own without a nudge, even having to hold it back with the middle finger of the left hand and then the index finger of the right hand in order not to hold it back with the left hand. Maybe it's not the capacitor but the battery?

[михаил потапыч]

Integer:

From 1:40 onwards, something about it starts spinning on its own without a nudge, even having to hold it back with the middle finger of the left hand and then the index finger of the right hand in order not to hold it back with the left hand. Maybe it's not the capacitor but the battery?

No, there's no sound.)

[Igor Maslov]

Mathemat:

And you can reduce the momentum in a different way - just by ripping off a piece at the same speed. The speed won't change, but the momentum will drop.

Absolutely agree. Still, how do you think the speeds of the two carts will change? By my logic, it won't, and neither will a cart that's just dumping snow into the middle of nowhere.

Edit: Stop! I meant idealised carts... If you take into account the friction, the sailing of piles of snow, obviously different heights, the megabrain itself and its shovel - then yes. I agree with everything.

[Dmitry Fedoseev]

Mischek:
Nah, there's no sound.)

But you can see there wouldn't have been a sound, a little twist.

[Sceptic Philozoff]

muallch: Absolutely agree. Still, how do you think the speeds of the two carts will change? By my logic, it doesn't, and neither does a cart that's just dumping snow into nowhere.

I don't know what happens to the speeds. But the momentum is changing.

And the braking of the carts happens because the momentum drops.

The idea is that this is what happens (with the cart working for time dt):

• An empty cart is walking and snow is falling on it. The momentum does not change, although the cart slows down a bit.
  
• Then MM throws the snow. The momentum changes less, but the speed doesn't change.
  

As a result, the speed is slightly less than it was before the snowfall. And the mass of the cart remains the same. It's as if it turns out that the cart can stop even without friction. But we need an equation here.

[михаил потапыч]

Integer:

But you can see there wouldn't have been any sound, a little twist.

I mean the fan can be turned by the directional air from the other fan

[[Deleted]]

Integer:

It's not a battery, it's a capacitor, I bought it in chip and dale myself. I needed a 6 volt, but they didn't have any, so I bought a 16 volt one, but it's bigger in size. It might start spinning on its own. When it doesn't spin, it beeps.

[Dmitry Fedoseev]

DmitriyN:
It's not a battery, it's a capacitor, I bought it myself in chip and dale. I needed a 6 volt, but it wasn't available, so I bought a 16 volt, but it's bigger. It might start spinning on its own. When it doesn't spin, it beeps.

How does it beep, maybe aliens are transmitting a message in morse code? If you hadn't written about the capacitor voltage, I'd have been on the verge of believing... You need a big one to hold the batteries. The case is from a capacitor and the batteries are inside.

[Igor Maslov]

Mathemat:

I don't know what happens to the speeds. But the momentum is changing.

And the braking of the carts happens because the momentum drops.

Ideally, this is what happens (with the cart working in time dt):

• There's an empty cart going by, snow is falling on it. The momentum does not change, although the cart slows down a bit. (1)
  
• Then MM throws the snow. The momentum changes downwards, but the speed does not change. (2)
  

As a result, the speed is slightly less than it was before the snowfall. And the mass of the cart remains the same. It's as if it turns out that the cart can stop even without friction. But here we need some equations.

1 This is true if the speed of the snow is less than the speed of the cart. If the speed of the snow is equal to the speed of the cart, the total (cart + arriving snow) momentum will increase, but the speed will not.

2. Yes.

PS. If the snow falls on the cart naturally - falling from the sky - then naturally the speed of the cart will fall.