posted by Fred .
(1) A helium atom consists of two protons (charge +2e) and two electrons (charge -2e) that are an average of 4.3 x 10^-11 m apart. Find the electrical force between them. Find the gravitational force between them. What is the ratio of gravitational to electrical force?
(2) A charge q1=7.8x10^-6 C is placed at the origin. q2=-3.4x10^-6 C is placed at y=-1 m, x=2 m. q3=-9.2x10^-6 C is placed at y=4 m. What is the total force on q1? On q3?