the LDR is connected in series with a fixed resistor of resistance 10 k ohms and a 4.5 battery. the total resistance at 30 lux is 22000 ohms

Suppose that three astronomical objects, 1, 2, and 3 are observed to lie on a line, and the distance from object 1 to object 3 is d. object 1 has four times the mass of object 3, and seven times the mass of object 2. find the distance between objects 1 and 2 for which the net force on object 2 is zero.