Condensed aerospace science and technology experts Xiaosi's "penguin suit", fluorescent cells that flash and flash, five ways of "twisting" in space, beautiful water film experiments... I believe that at the "Tiangong Classroom" on December 9, many people experienced a magical science fiction journey.
However, a 60-minute science class doesn't quench thirst.
While the three astronauts of the "Feel Good Ride" brought us these "exclamation points", they also aroused the curiosity of many people: What would be the effect if these space experiments were reproduced on Earth? What other similar and interesting experiments are there?
On December 12, Science and Technology Daily invited Li Yili, the first overall deputy chief designer of the Shenzhou spacecraft, and Dr. Chen Zheng, a member of the space teaching science expert group, to open a "Tiangong Classroom" and "Improvement Class" at Beijing Bayi School to tell the dream-chasing process of astronauts, comprehensively review scientific experiments, and straighten the question marks in the hearts of the audience.
Students who miss the live broadcast of the improvement class should not panic, the series of videos will be released on December 16 in tencent product youth mode "Master Lecture Hall for Children". This is a science lesson that makes children clap their hands and praise, and the heavyweight science giants interpret scientific knowledge in a funny and simple way. They share rich life experiences while stimulating children's curiosity and imagination to explore the world of science. With the wisdom of the master, open the future vision for the teenager.
If space opens a weightlifting event
Lifting up the earth is not a dream!
"Imagine if we had a Games in space, which event would break the record?" Chen Zheng asked first.
"High jump or long jump!" "Javelin!"" Shoot!" The students scrambled to answer.
"I want to break the record of weightlifting projects the most, and even want to lift the earth!" Chen Zheng told everyone that in space, weight lifting is relatively easy to achieve.
Chen Zheng also said that although the space station is in a microgravity environment, everyone is as light as a swallow, but at the same time loses the forward power provided by the friction of the ground, so it will be difficult for people to walk in space. This surprised many students who thought they could run faster in space because they were lighter.
After some interaction, Chen Zheng picked up the Changping frame gyro to explain to everyone. "When rotating at high speeds, the gyroscope has a fixed axis, and no matter how the normal flat frame is rotated, the gyroscope always maintains one direction." Chen Zheng further explained that if a gyroscope is assigned a direction, at any time, we only need to compare the angle between the gyroscope axis direction and determine the current direction. This is the core principle of gyroscope navigation.
In addition to the GPS navigation familiar to the public, based on the inertial navigation system, the gyroscope can work without signal changes at any time and play a navigation role. That is to say, whether it is on the ground, at sea, in the air or even in the deep sea, underground platform, you can know where you are anytime, anywhere.
Learn angular momentum conservation from the Cats
After the end of the "Tiangong Classroom", even Teacher Ye Guangfu himself did not expect that he had gone out of the circle with "Zuo Yao Right Twist" and became the highest "space turn model" in China.
Chen Zheng said that the core keyword of the space turn experiment is called angular momentum. Angular momentum is a physical quantity that describes the rotation of an object.
In this "improvement class", Chen Zheng became a "ground model", standing on a turntable that can rotate freely, in the absence of external torque, the upper body will be left, and the lower body will involuntarily go to the right. This is a simple and intuitive manifestation of conservation of angular momentum in life.
Chen Zheng also specifically mentioned the process of the cat landing. When the cat is in the air, it can circle the body and then twist and stretch, the body will not be fixed in a straight line during the process, and the turn over will be completed while maintaining the conservation of angular momentum, so the cat will always land on the ground first.
So, how do we turn gracefully like the "cats" while ensuring conservation of angular momentum? Chen Zheng personally went to the battle, showed an interesting posture such as "freestyle" on the turntable, and really turned! "Although I am relatively fat and my posture is not good, this action is very effective." Chen Zheng laughed.
Then, in order to present a simpler way to turn, Chen Zheng picked up a rotating wheel, clasped his hands, straightened his arms, and easily turned up.
Magical "water" experiments
Knock on the blackboard! Students who listen carefully must remember that when Teacher Wang Yaping put the ping-pong ball in a cup filled with water, the ping-pong ball could not float. This is because under the conditions of space microgravity, the internal pressure of the liquid is equal everywhere, and there is no longer a buoyancy caused by the pressure difference between the upper and lower surfaces. In other words, if an iron ball is placed on the surface of the water in space, it will not sink.
This time, Chen Zheng did the same experiment, and the ping-pong ball easily floated. This verifies that gravity and buoyancy exist at the same time. "In the microgravity environment of the space station, because every part of the water does not need to carry the water around it, it is floating in the air. Therefore, the pressure of the water in the cup in space is the same, put into the ping-pong ball, the forces cancel each other out, and the buoyancy disappears. Chen Zheng said.
Next, Chen Zheng "transformed" a sink and made a rectangular "bubble". He told everyone that we are accustomed to adding hand sanitizer, dish soap, soap liquid, etc. to the water to make a water film, because these surfactants can reduce the surface tension of water, in space, water droplets do not have gravity interference, with the help of solid water rings, water is easy to form a film. This is the knowledge point of "liquid surface tension", attracted by internal molecules, liquid surface molecules have a tendency to be pulled into the interior, resulting in the surface like a tight rubber film, this tightening force that promotes the contraction of the liquid surface is the surface tension.
In order to review the "water balloon optics" experiment, Chen Zheng used a pen to draw a left arrow on the paper, put the beaker filled with water in front of the piece of paper, when the water flooded the arrow, a magical thing happened, and the arrow in the cup reversed its direction! Chen Zheng explains: "This experiment is similar to a 'double portrait' in space, where a convex lens can present an inverted real image outside of 2 times the focal length. ”
In order to recreate the magic of the "double image" on the ground, Chen Zheng took the empty test tube, made an air column, and inserted it into the beaker that had just filled with water. The direction of the arrow observed through the empty test tube is just the opposite of the direction of the arrow observed in other positions in the beaker, and the students are hooked!
The vast universe is much more interesting than that. In response to a question from his classmates, Chen Zheng said that every night when you look up at the stars, nature has proved to you that the speed of light is limited; when the weather is good, people can see very distant stars, maybe 5 years ago, maybe 50 years ago, or even millions of years ago... What we see is exactly like a star version of the "epic".