Pretty sure it's asking for escape velocity FROM 1x10^17 m away from Earth, so just sub that as r and you're done!
Question:
If they tell you the torque acting on the WHOLE coil, would the torque acting on ONE side be half of the original torque?
Totally missed that question, sorry Katniss! Think you are almost definitely right pikachu too, cheers heaps
Hmm, that's an interesting question. Torque is a rotational force, I don't
think it would quite make sense to define it on one side of the coil only. Because if you separate one half, it's more just a linear force on one side if you catch my drift? Have never really thought about it before!
If you loosen the definition a bit though, I think it would be! The torque on a coil is generated by the forces acting on either side, and those forces are equal in magnitude. So yeah, I think it stands to reason that the torque would be half