Posted by Ginger on .
11. An object with a charge of +6.0 µC is 0.30 m from a second object and experiences an attractive force of 1.80 N. What is the magnitude of the charge on the second object? (µC = 1.0 × 106 C) (Answer: 3.0 µC)
Can someone please explain how to do this problem? I don't just want the answer, but i need to know the correct way to calculate it.

Physics 
Elena,
F=k•q₁•q₂/r²,
k =9•10⁹ N•m²/C²,
q₂ = F•r²/k•q₁ = 1.8•0.3²/9•10⁹•6•10⁻⁶ =
=3•10⁻⁶ C = 3 μC
Due to the attraction of the charges
q₂ =  3 μC