Question

1) Three point charges are arranged on a line. Charge q 3 = +5.00 nC and is at the origin. Charge q 2 = -3.00 nC and is at x = 4.00 cm . Charge q 1 is at x = 2.50 cm .

a)What is q1 (magnitude and sign) if the net force on q3 is zero?

2)Imagine two 1.5 g bags of protons, one at the earth's north pole and the other at the south pole.

a)Calculate the gravitational attraction that each bag exerts on the other.

b)Calculate the the electrical repulsion that each bag exerts on the other.

Answer 1

(1) For the net force on charge q, to be zero, the force on this charge q, by g, must be same as the force on this charge q, by g,, but they both should act in opposite direction. Thus, the net force oną, is, F = F, - F 0 = F, - F A = F, q. (3.00 nC (4.00 cm) This, the magnitude of the charge q, is 1.17 nC and the sign is "+". Then only the charge q, repels the charge q, and the charge q, attracts the charge q,. (2.5 cm) -1.17 nC (2) (a) The gravitational attraction between the two bags is, Gm, m. F. 1 kg (6.67×10")(1.5g)(15g) 1000 g. (2x6371x10' m) = 9.243x10-31 N (b) The total charge of each bag is, = ne .e 1.5 g (1.6x10- C)=1.437x10° C %3D 1.67x10-* g The electric repulsion between the two bags is, kq,9. F. D² %3D (9x10° )(1.437x10 c)(1.437x10 C) (2x6371x10' m) =1.145x10 N