A balloon, when rubbed against denim, gains a charge of -10μC. The force between the balloon and the denim when they are separated by a distance of 5 cm is:

Question

michele_laino · Answer

since the electric charge is conserved, then the denim will gain a charge of  
+10*10^-6 coulombs
The requested force, has the subsequent magnitude:
$$\large F = K\frac{{{Q_1}{Q_2}}}{{{r^2}}} = 9 \times {10^9}\frac{{ - 10 \times {{10}^{ - 6}} \times 10 \times {{10}^{ - 6}}}}{{{{\left( {5 \times {{10}^{ - 2}}} \right)}^2}}} = ...?$$