The diagram below shows three masses at the corners of a square of sidesd=1.10m.Here,m₁=m₂=mandm₃=5.10mwherem=4.00kg.

(a) What is the magnitude of the gravitational field at the center of the square due to these three masses? (b) Suppose the two massesm₁andm₂are not equal. What value ofm₁will produce a gravitational field at the center of the square directed vertically down?