At 15:40 on December 9, 2021, the first lesson of "Tiangong Classroom" was officially opened. Shenzhou 13 crew astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu transformed into "space teachers" to give a wonderful lecture on the China Space Station and broadcast live to the world.
The "Tiangong Classroom" is a continuation of the "Space Teaching".
In 2013, astronaut Wang Yaping, assisted by Nie Haisheng and Zhang Xiaoguang, gave his first space lecture during the Shenzhou 10 mission, demonstrating experiments such as quality testing, pendulum motion, gyro motion, and making water films and water balloons. After 8 years, Chinese astronauts once again conducted space teaching, which is also the first space teaching activity on the Chinese space station.
Compared with the first "space classroom", the podium of this "Tiangong Classroom" is larger, which is in the space station independently built in China, and there will be two experimental modules of "Asking the Sky" and "DreamIng" in the future; the content of the course schedule is also richer, adding new links such as space cytology research experiment display, buoyancy disappearance experiment, and effervescent film experiment.
Do you remember the 5 basic physics experiments about "Teaching in Space"?
On June 20, 2013, China's first space teaching activity was successfully held, and the Shenzhou 10 astronauts demonstrated five basic physical phenomena in the weightless environment at Tiangong-1.
Quality measurement experiments
Gravity is caused by the attraction of the Earth, and because there is no Gravitational Force in space, it is impossible to measure gravity with a spring dynamometer. How is mass called in space? Astronaut Wang Yaping explained that the principle of weighing equipment in space is to use the constant force generated by the "spring-cam" mechanism and the grating speed measurement system to measure the acceleration of body movement, and calculate the mass of the body according to Newton's second law (f =ma).
Pendulum motion experiment
Small balls on a frame in space do not swing back and forth like they do on the ground. In space, because the weightless ball has no recovery force, it cannot do reciprocating swing, but giving the ball a small initial velocity can make a circular motion around the pendulum axis, but on the ground it needs a large enough initial velocity to achieve.
Gyro motion experiments
In space, give the stationary gyroscope a primordial force and see the gyroscope tumbling in its previous motion. Give the spinning gyro the same force, and find that the spinning gyro shakes and moves forward. Because the high-speed rotating gyro has good orientation, many devices in the space capsule use the principle of gyroscope orientation.
Water film and water balloon experiments
In space, water doesn't flow out on its own. Wang Yaping said, "The poet Li Bai could not write verses in space that flowed down three thousand feet. "When the astronaut squeezes out a small droplet of water, the droplet is suspended in the air. The astronauts also demonstrated how ordinary water makes a membrane of water. Since the surface tension of space water plays a role, the water film will not easily break when it shakes back and forth. Add water to the water film, and the water film gradually thickens into a water balloon. The astronauts also used a syringe to inject the red liquid into the water balloon, and found that the liquid slowly dispersed, and the transparent water ball turned into a red water ball.
The knowledge point behind the "Tiangong Classroom" experiment
In the 60-minute teaching time of "Tiangong Classroom", the astronauts completed 8 teaching projects, including the display of work and life scenes in orbit, the experimental display of space cytology, the space turn, the buoyancy disappearance experiment, the water film tension experiment, the water balloon optics experiment, the effervescent film experiment and the interaction between heaven and earth, each of which contains different physical knowledge.
Space Turn Knowledge Point: Angular Momentum
Turning around, this ordinary action with zero difficulty coefficient on the ground, but hidden physics knowledge in space.
To achieve a turn in space, one arm needs to be circled. As the body rotates, the arm retracts and rotates faster. At the heart of this turn experiment is angular momentum. Angular momentum is a physical quantity that describes the rotation of an object. What this test shows is that in a microgravity environment, the astronauts in the case of not touching the space station, similar to the ideal state to verify that "there is no external moment, the object will be in the conservation of angular momentum." When the astronaut's upper body is rotated to the left, according to the principle of angular momentum balance, the lower body will turn to the right.
When the astronaut stretches the body, because the mass distribution is farther away from the axis of rotation, the rotation inertia is relatively large, so the angular velocity is slowed down, in layman's terms, it is slower. When the limbs are withdrawn, the rotation inertia is small, the angular velocity will increase, and the intuitive feeling is that the rotation speed becomes faster.
Buoyancy disappearance experiment Knowledge point: Buoyancy and gravity are associated
In space, ping-pong balls are not placed in the water, but stay in the water. This is because buoyancy is generated with gravity, in the space weightless environment, the internal pressure of the liquid is equal everywhere, there is no longer a pressure difference between the upper and lower surfaces, and the buoyancy almost disappears.
This experiment shows the phenomenon of buoyancy and gravity. Buoyancy arises from the difference in pressure of the liquid at different depths caused by gravity. When gravity disappears, the internal pressure of the liquid is the same, and the buoyancy is also gone. However, it is difficult for the buoyancy on the surface of the earth to disappear, and this experiment is difficult to visualize intuitively. Under the microgravity conditions of the space station, the associated relationship between buoyancy and gravity can be very clearly visualized.
Water Balloon Optical Experiment Knowledge Point: Convex Lens Imaging Principle
An inverted image can be seen in the water balloon, which is the principle of convex lens imaging. A bubble is injected into the water balloon, and two images of one positive and one reverse can be seen.
This experiment demonstrates three physical principles simultaneously. First, in the weightless environment, the water droplet will shrink into a water ball close to a perfect sphere under the action of surface tension, and on the ground, because of the influence of gravity, the water droplet appears as a water drop shape, and it is almost impossible to obtain a perfect water ball. Second, the water balloon can be seen as a convex lens, and if you stand outside the twice the focal length of this convex lens, you will see a real image of an inverted stand. The third is to punch a bubble into the water balloon, because the buoyancy in space disappears, the bubble will not float out, it will honestly stay inside.
Effervescent tablet experiment Knowledge point: microgravity environment
The effervescent film experiment conducted by the astronauts is an interesting experiment in this space lecture. The effervescent tablets are placed in the water to produce a large number of bubbles, and the bubbles do not emerge from the water balls. The water balloon in the experiment resembles a blue earth.
This is because the space station is in a microgravity environment, and through experiments, we can know that in the microgravity environment, many physical phenomena and the ground environment are different.
Space science education will be one of the important functions of the space station
With the long-term operation of the Chinese space station in orbit, China's first space science education brand "Tiangong Classroom" will be launched in series, and Chinese astronauts will serve as "space teachers" and adopt the collaborative interaction of heaven and earth. In the future, China will carry out space science education activities in a series of ways.
Yang Yuguang, vice chairman of the Space Transport Committee of the International Astronautical Federation, said that the future teaching content is broader, not limited to physical and chemical phenomena under microgravity conditions, but also can introduce space science research and engineering research. Secondly, more in-depth and influential activities will be carried out, china already has a student-made Cubestar, with the space launch mission into space, the future can also have student-designed space science experiments into space.