Why isn’t a drinking bird perpetual motion?
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Don’t feel bad for not understanding. The toy baffled Einstein for months on end. He wanted to understand how it works without breaking it apart first
If you have liquid water in a room that’s below 100% relative humidity, it wants to evaporate until the room is fully saturated with water vapor. When a process wants to happen, you can sometimes put a minor obstacle in its way so it’ll overcome the obstacle and do useful work for you. That’s the basic idea of how hydroelectric dams work.
It’s hard to turn heat into motion because motion is more organized than heat, and everything in the universe wants to get less organized. But a room full of water vapor is less organized than a glass of water in a dry room by a larger margin than a warm room is less organized than a cooler room and a moving bird. So when the drinking bird runs, the room containing the bird and the water gets less organized, even if some parts of it (the bird’s motion) have get more organized in the process.
Don’t feel bad for not understanding. The toy baffled Einstein for months on end. He wanted to understand how it works without breaking it apart first
If you have liquid water in a room that’s below 100% relative humidity, it wants to evaporate until the room is fully saturated with water vapor. When a process wants to happen, you can sometimes put a minor obstacle in its way so it’ll overcome the obstacle and do useful work for you. That’s the basic idea of how hydroelectric dams work.
It’s hard to turn heat into motion because motion is more organized than heat, and everything in the universe wants to get less organized. But a room full of water vapor is less organized than a glass of water in a dry room by a larger margin than a warm room is less organized than a cooler room and a moving bird. So when the drinking bird runs, the room containing the bird and the water gets less organized, even if some parts of it (the bird’s motion) have get more organized in the process.
Because it’s powered by the water evaporating from its head which cools the head relative to the lower body and the slight pressure differential between the top and bottom is enough so that the fluid at the bottom rises to the top and makes it top heavy enough so that it takes a dip again. In this case, the “fuel” is the water, and in order for this process to take place the head is always covered with a material like felt which can absorb and hold onto the water, otherwise it would slide off the glass tube. So every time the bird dips, it takes a bit of water from its cup, and it will hold it in the felt until it evaporates. So the water level in the cup is slowly decreasing, as in the energy being consumed is the phase shift of the water.
Because it’s powered by the water evaporating from its head which cools the head relative to the lower body and the slight pressure differential between the top and bottom is enough so that the fluid at the bottom rises to the top and makes it top heavy enough so that it takes a dip again. In this case, the “fuel” is the water, and in order for this process to take place the head is always covered with a material like felt which can absorb and hold onto the water, otherwise it would slide off the glass tube. So every time the bird dips, it takes a bit of water from its cup, and it will hold it in the felt until it evaporates. So the water level in the cup is slowly decreasing, as in the energy being consumed is the phase shift of the water.
It requires heat differential. If you run the “drinking bird” in perfect heat equilibrium, it doesn’t work.
Can’t escape the 2nd law thermodynamics with a childs toy.
It requires heat differential. If you run the “drinking bird” in perfect heat equilibrium, it doesn’t work.
Can’t escape the 2nd law thermodynamics with a childs toy.
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