Determine the gravitational potential energy of a rod-cylinder system where a thin, uniform rod of length L and mass M is aligned along an axis and a small uniform cylinder with mass m located a distance y from one end of the rod along the same axis. Assume y is significantly greater than L. Take the potential energy to be zero when the rod and cylinder are infinitely separated.

• A. U = $-\frac{GmM}{y}$
• B. U = $-\frac{GmM}{L}$
• C. U = $-\frac{GmM}{L+y}$
• D. U = $-\frac{GmM}{L-y}$

Answer: (A)