1. Two small objects, each with a charge of 4.0 uc, are held together by a 0.020 m length of insulating string as shown. The objects are initially at rest on a frictionless,
non-conducting surface.

Hi, your answer is not correct. this is a cumulative  

Ireally don’t know

In atoms, the electron carries a negative elementary or unit charge; the proton carries a positive charge. the two types of charge are equal and opposite. in an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus.

You need to calculate the string in between two masses