# weightlessness and forces conceptional question

I am currently learning about forces and newton's laws of motion. I have a question in my book which I don't understand though... Here it is:

(note: I dont want the answer I just want to understand what this question is asking.)

The question: The "mechancial arm" on the space shuttle can handle a 2200kg satellite when extended to 12m. Yet on the ground, this remote cannot support its own weight. In the "weightlessness" of an orbiting shuttle, why does the RMS have to be able to exert any force at all?

My main problem in the question is what does it mean by saying this remote cannot support its own weight.

Thanks for the help. :)

• By "cannot support its own weight" they mean that if you bolted on end to the ground or a solid wall and tried to use the arm as a crane, it couldn't even lift the other end much less be used to support other objects. – dmckee --- ex-moderator kitten Feb 14 '15 at 18:48
• but how is it related to the question? And what hint does it give? – mariam.. Feb 14 '15 at 18:49
• It can't pick up the end of it's own arm on the Earth, but it can maneuver a 2 ton mass in orbit. You are expected to think about how those two statements can be true and to understand something about the nature of weight and mass from those considerations. – dmckee --- ex-moderator kitten Feb 14 '15 at 18:52
• so here is what I thought of until now: On earth the remote has a lot of weight because earth exerts a lot of gravitational force on it (a=F/m). In space, there is no weight but the mass stays the same. This large mass can act as a counter weight to other objects. What more does my answer need, I feel it isnt complete yet? – mariam.. Feb 14 '15 at 19:06