| On the earth, we are not very conscious of the difference between mass and weight. In space, it becomes very obvious. This heavy mass of 50kg is weightless - it will float in front of Mark if he lets it go. But has inertia, and when moving it has momentum. In other words, it takes a lot of force to push it, and to stop it. Working with heavy equipment in a large space like the ISS requires that the cosmonauts be familiar with this feeling before they arrive at the station, hence the training exercise. |
