A science class from above Earth(2)

Wang Yaping, the second Chinese woman in space, demonstrated how a variety of objects — from a spinning toy to a bubble of water — behave in space. Xinhua

It was followed by an experiment where she held out a small ball tied to a string. "What will happen if I let the ball go?" she asked.

The ball did not swing as it would on Earth but stayed suspended. When she pushed the ball gently, the ball moved in a circular motion, which stirred the classroom a bit.

Wang later pushed a static gyro and a moving gyro to change the way they move.

What appeared to excite students most were the experiments with water.

Wang made a film of water with a metal ring, and then a ball of water to explain how zero gravity magnified surface tension.

Chen Yumeng, 16, a student from Beijing No 80 High School, said the water ball experiment was an eye-opening experience, as it is impossible to see on Earth.

On Earth, the effect of gravity and buoyant force will make air ascend inside water, but in low gravity, air bubbles stay inside the water, she said.

"The demonstration is too short, just 40 minutes," Chen said. "I wished the astronauts could do more experiments up in space."

Xiao Jianqiao, a student from Beijing No 2 High School, said he never imagined the astronauts would demonstrate objects in low gravity in such innovative ways.

"Today it's really a joyful surprise that our Chinese astronauts did things like inject red liquid into a ball of water, making its shape stand out."

After the experiments, astronauts also answered questions from students, including the difference between up and down in space, the recycling of water in the orbiter, space debris, the impact of a gravity-free environment on the human body and the view through windows of Tiangong-1.