The space lectures are mainly aimed at primary and secondary school students, enabling them to understand the characteristics of the movement of objects under weightlessness, the role of liquid surface tension, and deepen their understanding of basic physical concepts such as mass, weight and Newton's laws. Wang Yaping explains and demonstrates experiments in the Tiangong.

1, experiment (mass measurement)

In Shenzhou-10, there is a special "mass measuring instrument". Nie Haisheng, the assistant teacher of "space lectures", fixed himself at one end of the bracket, and Wang Yaping pulled the spring connected to the motion mechanism to the designated position. When he let go, the tension caused the spring to return to its initial position. In this way, Nie Haisheng's weight - 74 kilograms - was measured.

Revealed content: Newton's second law

On this issue, Wang Yaping had an explanation, "In fact, it's Newton's second law F = ma." That is, the force on an object = mass × acceleration. If you know the force and acceleration, you can calculate the mass, "spring cam mechanism that produces a constant force. That is, the force that just pulled the aide back to its initial position. In addition, a grating velocimetry system is designed to measure the acceleration of the body's motion."

2. Experiment (Single Pendulum Motion)

On a T-shaped stand, a small ball is attached to a thin string. This is a common experimental setup in physics class - a single pendulum. Wang Yaping pulled the ball up to a certain height and then let it go, and the ball swung at a very slow speed as if it were possessed. Then, Wang pushed the ball with his finger, and it began to move in a circle around the axis of the stand.

Revealed content: weightlessness in space

Zhejiang University College of Aeronautics and Astronautics experts: on the ground, the period of motion of a single pendulum is related to the length of the pendulum, gravity and acceleration. But in the state of weightlessness, there is no more repulsive force, the steel ball is stationary in the original position. At that point, the thin rope is not giving the ball tension.

Pushing the ball by hand is equivalent to giving the ball an initial velocity, while the thin rope gives the ball tension, which balances the centrifugal force, and the ball moves in a circle around the axis of the stand. Without the tension of the rope, the ball would be in uniform linear motion. On the ground, on the other hand, the resistance of the air makes the object go slower and slower, and gravity makes the object fall downward.

3, the experiment (gyroscopic movement)

Wang Yaping took out a gyroscope, gently pushed the hand, the gyroscope unexpectedly tumbled forward, the line of travel is unpredictable. She then took out another gyro, pumped it and then pushed it with her hand, and it flew forward along a fixed axis.

Revealed: conservation of angular momentum

Special teacher Luo Xinggao: A spinning gyroscope has a fixed axis. The larger the rotor's moment of inertia, the better the stability; the larger the rotor's angular velocity, the better the stability. Fixed-axis behavior obeys the law of conservation of angular momentum -- in the absence of an external moment, the angular momentum of an object remains constant.

The instantaneous disturbance force applied by the astronauts cannot produce a sustained moment, and because of the conservation of angular momentum, the axis of rotation of the high-speed rotating gyro will not change much. The reason why this is difficult to realize on the ground is that factors such as the interference torque generated by the friction between the gyro and the ground change the angular momentum of the gyro, gradually reducing its rotational speed and not keeping the rotational direction well.

4. Experiment (making a water film and a water balloon)

A metal ring inserted into a bag of drinking water and withdrawn formed a water film. This is difficult to achieve, at ground level, because gravity would tear the water film apart. So, is this water film sturdy? Lightly shaking the metal ring, the water film did not rupture, but threw out a small droplet of water. A plastic sheet with a Chinese knot pattern was then attached to the surface of the water film, which remained intact.

More miraculous moments: in the second water film, with a drinking bag constantly filled with water, the water film quickly grew into a large crystal clear water ball. The water balloon has a series of bubbles inside, removed with a syringe, but the water balloon is not damaged in any way. Finally, Wang Yaping injected red liquid, red slowly spread, the water balloon into a beautiful "ruby".

Mystery: Liquid surface tension

The mutual attraction between molecules within the surface layer of a liquid is surface tension, which can cause the liquid surface to shrink automatically. Surface tension is caused by a large cohesion between the liquid molecules, in space and the ground droplets produce surface tension are the same principle. In weightlessness, there is no more gravity squeezing between the droplets, and the droplets all form the most perfect spherical shape under surface tension.

Extended information:

Lecture background

In mid-June 2013, the In mid-June 2013, Chinese female astronaut Wang Yaping became China's first "space teacher" by teaching primary and secondary school students on board Tiangong-1, China's first target vehicle. In order to do a good job of this popular science education activity, the China Manned Space Engineering Office, together with the Ministry of Education, China Association for Science and Technology and China Central Television (CCTV), carried out a systematic and thorough planning of the activity.

And completed the courseware, teaching aids production and ground classroom preparations, the astronauts are also related to training, this activity will be in the combination of body operation during the opportunity to carry out, the specific time will be taken into account comprehensively in the flight mission arrangements, the astronauts rest and relaxation and measurement, control and communication and other security conditions to determine the final.

Lecture significance

As the second country to complete space lectures after the U.S., the space lectures will not only enhance the interest of the whole population in space, but will also promote the development of large-capacity information processing industry in the world from the perspective of application, and the advent of the big data era will become an opportunity for the development of large-capacity information processing industry in the world.

At the same time, it also means that China has been able to conduct real-time monitoring of extraterrestrial spacecraft for at least 40 minutes, which means that China already has the ability to make adjustments and monitor intercontinental missiles throughout the process.

Baidu Encyclopedia - Space Lectures