人造地球卫星、宇宙飞船、航天飞机进入轨道后,绕地球做圆周运动,其中的人和物将处于失重状态。做圆周运动的物体,速度的方向是时刻改变的,因而具有加速度,它的大小等于卫星所在高度重力加速度的大小。这跟以重力加速度下降的升降机中发生的情况类似,航天器中的人和物都处于完全失重状态。你能够想象出完全失重的条件下会发生什么现象吗?物体将飘在空中,液滴绝对呈球形,气泡在液体中将不上浮。宇航员站着睡觉和躺着睡觉一样舒服,走路务 Artificial Earth satellites, spacecraft, space shuttle into orbit, circular motion around the Earth, in which people and things will be in weightlessness. A circular object, the direction of the velocity is momentarily changing, and therefore has an acceleration equal to the magnitude of the gravitational acceleration at the height of the satellite. This is similar to what happens in elevators where the acceleration of gravity decreases, and people and things in the spacecraft are in total weightlessness. Can you imagine what happens under total weightlessness? Objects will float in the air with absolutely spherical droplets, and the bubbles will not float in the liquid. Astronauts standing asleep and lying asleep as comfortable, walking service