[Bridge: Submerged vertical spring-mass oscillator (spring scale under water)] A solid cylindrical bob of mass 0.50kg and volume 4.0×10−4m3 is hung from a light vertical spring of force constant 200N m−1. The arrangement is lowered gently until the bob is fully immersed in water and allowed to come to static equilibrium. The bob is then set into small vertical oscillations about this new equilibrium position.
Find the largest amplitude (measured along the spring direction) for which the spring never becomes completely slack during the motion.
(A) 24.5 mm
(B) 5.0 mm
(C) 4.9 mm
(D) 9.8 mm