18. When 1.6 mathrm(~kg) point charge is 1.5 mathrm(~m) from a second point charge, the gravitational force each one experiences is 573 mathrm(~N) . What is the mass of the second charge? Given: & Work: Formula: & Answer: 2.83 times 10^10 mathrm(~kg) b. 1.2 times 10^11 mathrm(~kg) c. 1.2 times 10^12 mathrm(~kg) d. 8.5 times 10^12 mathrm(~kg) 19. Two electrons are 20 mathrm(~m) apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other? (c=-1.60 times 10^10 mathrm(C)) Given: & Work: Formula: & Answer: a. 1.2 times 10^-37 mathrm(~N) b. 5.8 times 10^11 mathrm(~N) c. 2.5 times 10^-10 mathrm(~N) d. 1.6 times 10^11 mathrm(~N) 20. The force of attraction that a -40.0 mathrm(C) point charge exerts on a +108 mathrm(C) point charge has magnitude 4.00 mathrm(~N) . How far apart are these two charges? Given: & Work: Formula: & Answer: a. 1.38 times 10^9 mathrm(~m) b. 1.9 times 10^4 mathrm(~m) c. 3.12 times 10^6 mathrm(~m) d. 9.71 times 10^4 mathrm(~m)

18. To find the mass of the second charge, we can use the formula for gravitational force: Given:- Gravitational force (F) = 573 N- Distance (r) = 15 m- Mass of the first charge (m1) = 1.6 kgWe need to find the mass of the second charge (m2).Rearranging the formula to solve for m2: Substituting the given values: Therefore, the mass of the second charge is .19. To find the magnitude of the maximum electric force between two electrons, we can use Coulomb's law: Given:- Charge of each electron (q1 and q2) = -1.60 x 10^-19 C- Distance (r) = 20 mSubstituting the given values: Therefore, the magnitude of the maximum electric force that the two electrons exert on each other is .20. To find the distance between the two charges, we can use Coulomb's law: Given:- Force (F) = 4.00 N- Charge 1 (q1) = -40.0 C- Charge 2 (q2) = +108 CRearranging the formula to solve for r: Substituting the given values: Therefore, the distance between the two charges is .