A long limp spring is hung from a beam; the spring's bottom is 660 mm above the table. A 0.50 kg cylinder is hooked to the spring's bottom while the spring hangs relaxed. When the cylinder is dropped, it turns around just above the table, where the spring's bottom had been stretched to 10 mm above the table. Calculate the spring's stiffness.

A long limp spring is hung from a beam; the spring's bottom is 660 mm above the table. A 0.50 kg cylinder is hooked to the spring's bottom while the spring hangs relaxed. When the cylinder is dropped, it turns around just above the table, where the spring's bottom had been stretched to 10 mm above the table. Calculate the spring's stiffness.