Problem 2: Coulomb's law and multiple point charges Three point-charges are arranged as in the picture. Charge q is known to be positive, while charges Q1 and Q2 are unknown. We know however some information about them: the net force they exert on q points downwards, along the −y-axis as shown. A. Is Q1 positive, negative or could it have either sign? Explain. (Hint: How does Q1 contribute to F→net ?) B. Is Q2 positive, negative or could it have either sign? (Hint: How do Q2 and Q1 contribute to F→net ?)
