Two point charges of magnitudes + 5.00 C, and + 7.00 C are placed ...

[Alainaaa8]

Two point charges of magnitudes + 5.00 C, and + 7.00 C are placed along the x-axis at x = 0 cm and x = 100 cm, respectively.
 
  Where must a third charge be placed along the x-axis so that it does not experience any net force because of the other two charges? A) 4.58 cm
  B) 45.8 cm
  C) 50 cm
  D) 9.12 cm
  E) 91.2 cm

Question 2

Three point charges of magnitudes + 4.0 C, - 5.0 C, and - 9.0 C are placed on the x-axis at x = 0 cm, x = 40 cm, and x = 120 cm, respectively. What is the force on the - 9.0 C charge due to the other two charges?
 
  A) -0.55 N
  B) 0.55 N
  C) 0.64 N
  D) 0.41 N
  E) - 0.41 N

[ghepp]

Answer to Question 1

B

Answer to Question 2

D