Expert: Yang Chao, Ph.D. in Chemistry, University of Chinese Academy of Sciences
Reviewer: Li Xueyang, Postdoctoral Fellow, Dalian Institute of Chemistry, Chinese Academy of Sciences
This afternoon, the "Tiangong Classroom" of the Chinese space station launched the second space teaching activity and continued to adopt the method of dialogue between heaven and earth.
Space experiments are both fun and full of dry goods.
Even our lovely ice piers have gone into space and have been "forced" into teaching tools to explain this important law to you!
If you can't memorize it, then you're sorry for the ice teacher of space business!
Strange things happened after the ice pier was thrown?
In the space parabolic experiment, Teacher Wang Yaping used the top-flow ice pier as a teaching tool, and with a gentle stroke, he let the ice pier easily do several backflips, which if he gave up on the ground, the ice pier that left his hand would have fallen to the ground long ago.
Then Teacher Wang gently threw the ice pier in one direction, and the same ice pier did not fall "down" like on the ground, but moved forward at a nearly uniform speed along the direction of the throw, why is this?
This is to be explained by Newton's first law, Newton's first law is also known as the law of inertia, and you remember the definition in our junior high school physics book! When all objects are not affected by external forces, they always remain stationary or in a uniform linear motion state.
When the ice pier is thrown in one direction, the gravitational force of the earth and other celestial bodies provides a centripetal force for uniform circular motion, this centripetal force makes the ice pier and the space station rotate around the earth, but in the space station, it seems that the space station as a reference frame, the ice pier pier is basically no acceleration, because the ice pier has forward inertia, it can be approximately uniform linear motion. If no force is applied to the ice pier during the release process, the ice pier will remain stationary.
Why does Teacher Wang Yaping always rigorously emphasize that it is "approximate" uniform linear motion in the curriculum? This is because although Tiangong is in space, the space station will still be affected by other forces.
For example, the air in the space station will exert a very small resistance to the pier backwards when the ice pier moves forward, which is the air resistance, if the space station is "long" enough, the speed of the ice pier will gradually decrease (which may last for a long time) during the forward movement process, and eventually it will remain relatively stationary with the space station.
Will the moon be bigger and brighter when viewed from space?
Does the moon look bigger than if it would be closer to the moon in space on Earth?
No, the moon is 380,000 kilometers away from the earth, and the Chinese space station is only 400 kilometers away from the earth, which is a negligible distance compared to 380,000 kilometers, so looking at the moon on the space station is the same as looking at the moon on the earth.
But with no interference from the atmosphere and clouds, the moon seen on the space station will be clearer and brighter!
Moon seen on Earth (Source: Taken by the author)
What benefits can a weightless environment bring to humanity?
In a weightless environment, substances can be mixed more evenly
Just like the water-oil mixing experiment done by Teacher Wang Yaping, water and oil cannot be mixed uniformly on the earth, and will be layered due to different densities under the action of gravity.
In a weightless environment, the mixture can be mixed evenly, creating special alloys that are not possible on the ground.
Gallery copyright pictures, not authorized to reprint, please contact the original author
Crystals grow more evenly under weightless conditions
The "Space Protein Crystal Growth" experiment is an important scientific research project in manned spaceflight activities around the world.
Affected by gravity on the ground, it is particularly difficult to produce pure and large protein crystals, and under weightless conditions in space, protein crystals can grow more purely and in larger volumes than on Earth.
Experiments have also been carried out on the International Space Station to promote the growth of protein crystals, such as the crystallization of insulin, the high quality of insulin crystals grown in space, can form a different from the hexamer insulin crystals of the insulin monomer, compared to the monomer insulin, after injection hexamer can be gradually dissolved to transport the monomer into the bloodstream, which provides potential for the development of new insulin with a slower delivery rate, which is of great significance for diabetics to obtain better treatment.
Earth-grown insulin and space-grown insulin (Source: doi.org/10.1016/0022-0248(96)00325-9)
Microgravity metallurgy acquires new and exotic metals
Humans have been smelting metals for thousands of years, and with the development of space technology, metal smelting has gradually begun to be carried out in space.
Space smelting, also known as space metallurgy, is a specific ultra-high vacuum and weightless space environment in the space vehicle to smelt metals, gravity caused by a variety of interference can be eliminated to obtain a new and exotic metal.
In 1969, the Soviet Union completed welding and alloy melting and solidification experiments under space microgravity conditions on the Soyuz 6 spacecraft, creating a history of human space metallurgy. In microgravity conditions in outer space, surface tension and diffusion become the main controlling factors. Under microgravity conditions, the difference in density does not produce gravitational settling or buoyancy-induced floating, so bubbles in the liquid do not move upward due to buoyancy. For example, foam metal materials have received widespread attention due to their small density and strong impact absorption ability.