iss

[wendilla]

Just been watching the astronants on spacewalk on nasa live on here and was wondering how do they cope with the speed that the iss goes at. Does it slow down any when they are doing these outside the station tasks.

[Loosehead]

Speed is relative, as far as the astronauts are concerned their speed is 0 compared to the ISS. The Astronauts and Space station are all in freefall at the same speed, approx 7.7km per sec.

[squarebear]

That's right. It's similar to when you are walking down the aisle of a moving train. Although the train may be travelling at over 100mph, you appear to be moving at walking pace.

[ryepie]

The speed does not effect the astronuats one jot. To remain at a constant speed requires a net force of zero on a body, therefore the astronauts do not feel anything and could potentially travel at any speed and do their job. Remember there is nothing like air resistance for them to contend with, as you would feel if you stuck your head out of a car travelling down a motorway

Although strictly speaking the astronauts are accelerating but this acceleration is v close to the gravitational force we all know and love anyway; any object that is inserted in to orbit is given a lateral motion relative to its position above the surface of the earth. And depending on what height the object is, the right amount of lateral speed will ensure that it is in a constant state of free-fall. All objects orbiting the earth are in freefall due to the earth's gravity, but they are freefalling in such a way that the surface of the earth is constantly falling away from the object (due to the earth being spherical). That is why all objects in a geostationary orbit are at the same height (about 35,000-40,000 km) as that is the height at which the speed of free fall matches the rotation of the earth's surface.

[wendilla]

thank you for your replies you all have explained very clearly.