Final answer:
In equilibrium, the sum of the forces acting on an object is zero. q2 in Figure 1 is in equilibrium, and the net force acting on it is zero. Therefore, q1 can have any value as long as it creates a net force of zero on q2.
Step-by-step explanation:
In order to determine the charge q1 in Figure 1, we need to consider the concept of equilibrium. In equilibrium, the sum of the forces acting on an object is zero. In this case, q2 is in equilibrium, meaning the net force acting on q2 is zero. We can use Coulomb's law to calculate the force exerted on q2 by q, and set it equal to zero:
F = k * (q * q2) / r^2 = 0
Since q is given as 4.2 nC, we can plug in the values and solve for q2:
4.19 * 10^9 * (4.2 * 10^(-9)) * q2 / (0.04)^2 = 0
Solving for q2, we find that q2 is equal to zero. Therefore, q1 can have any value as long as it creates a net force of zero on q2.