Answer: a) see attach file; b) E=0; c)E=-1.65* 10^6 N/C
Explanation: In order to solve this problem we have to use the gaussian law which is given by:
∫E*dr=Q inside/εo
E for r=8 cm is located inside the conducting shell so E=0.
For r=13 cm we have to use above gaussian law considering the total charge inside a gaussian surface with radius equal to 0.13 m. ( see attach)
Answer:

Explanation:
From the law of conservation of energy
Energy lost by the spring, W=Kinetic energy gained, KE+Potential energy gained, PE+Work done by friction, Fr



The required distance from A to B is 
Answer: I am pretty sure that you should pick radio waves.
Explanation: The scientist should use radio waves. I think this because you can use the radio waves to analyze the signals from outer space. This will work much better than anything there, to analyze it the best possible.
The best I could do.