Two small balls of mass m each are suspended by equal threads of length L from two points separated horizontally by distance a. Due to their mutual gravitational attraction each thread makes angle θ with the vertical. Find the relation for θ.

Question

G1 Physics · Accepted Answer

Step 1: If each string inclines inward by θ, the separation between the balls is d = a - 2L sinθ. Step 2: Mutual gravitational attraction is F = Gm²/d². For either ball, equilibrium givₑ Tsinθ=F and Tcosθ=mg, hence tanθ=F/(mg). Step 3: Therefore tanθ = Gm/[g(a-2L sinθ)²]. This relation matches source option B.