Physics HW Help please - I'm stuck?

Question

Two tiny conducting spheres are identical and carry charges of -22.7 C and +53.2 C. They are separated by a distance of 2.16 cm. (a) What is the magnitude of the force that each sphere experiences? (b) The spheres are brought into contact and then separated to a distance of 2.16 cm. Determine the magnitude of the force that each sphere now experiences.

Answer 1

Vogel, aber es ist nicht wirklich so!

(a)♣ F= q1*q2/(4*pi *ε0*x^2) =

= -22.7*53.2 / (4*3.1416 *8.854e-12*0.0216^2) =

= -2.33e16 N; (minus showing attraction);

(b)♦ new q =(q1+q2)/2 =(-22.7 +53.2)/2 =15.25 C;

F= q*q/(4*pi *ε0*x^2) =

= 15.25^2 / (4*3.1416 *8.854e-12*0.0216^2) =

= 4.48e15 N; repulsion;

Answer 2

Electrostatic force is given by F = kq1q2 / r².

(a) F = ((8.99 x 10^9 Nm²/C²) x (- 22.7 C) x 53.2 C) / (0.0216 m)²

= 2.33 x 10^16 N

(b) Bringing the two spheres in contact causes them to carry charge equal but opposite in magnitude.

q (new) = (53.2 C - (- 22.7 C)) / 2 = ± 37.95 C

F = ((8.99 x 10^9 Nm²/C²) x (- 38.0 C) x 38.0 C) / (0.0216 m)²

= 2.78 x 10^16 N