Generally speaking, in the weightless environment of space, water should float in the air and assume a spherical shape, as shown in the picture below.
However, during the Shenzhou 13 space lecture, a photo of a water cup caused some confusion. From the picture, it can be seen that the water in the water cup seems to be firmly "locked" and does not float. out. What is the scientific principle behind this? Today, the editor will unveil the mystery in your mind.
Water does not float out of the cup because tension is at work
Water cannot float out of the cup. Behind this phenomenon is actually the surface tension of water at work. Even if the cup is turned upside down, the water will not flow down. , which is the characteristic of water in the weightless environment of space. In fact, surface tension also exists in liquids on the ground, but it is also affected by factors such as gravity and is not easily observed.
As we all know, on the ground, when the cup is full, the water will flow down along the wall of the cup. However, if you observe carefully, you can find that when the cup is not full, the water level will gradually rise. When it is higher than the rim of the cup, the water will not fall. , the surface of the water is like an inflated balloon. As the water increases, it gradually becomes plumper. Until it reaches a certain level above the rim of the cup, the water will splash down the cup wall. When the water is about to fall, the water surface seems to be tightly covered with a water film, preventing the water from flowing down. This is the liquid surface tension .
How do astronauts drink water in space?
In the weightless environment of space, since water will not flow downwards, how do astronauts "pour" water into cups? According to aerospace experts, there are many ways to put water into a cup. For example, first seal the cup with a film, then use a needle to inject water into it. After the water adheres to the cup, remove the film. If you drink water from a cup in space and the astronaut sucks it with your mouth, the water will fly out immediately, so you need to use a drinking bag or straw to drink water.
As for why when teaching in space and , the water cup can be placed on the table as smoothly as on the ground? This is actually very easy to achieve, just glue the tear-off buckles on the bottom of the cup and the table.
China Space Station Space teaching is a new way to open science education. Netizens can observe these details, which illustrates the importance of global space science popularization. In space teaching, almost every detail reflects the difference between heaven and earth, breaking people's daily life experience and original cognition. It allows the public, especially children, to rethink common phenomena in life, and invisibly conveys the attitude and spirit of respecting science.
Source: China's Aerospace
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