an 18 kg child is sitting on one end of a 5.0 m playground teeter-totter which has a pivot at its midpoint as shown. how far from the pivot on the other side should her 25 kg friend sit to balance the teeter-totter?

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.