Mass on a Spring: in the Figure, Two Masses, M

Multiple Choice

Mass on a spring: In the figure, two masses, M = 16 kg and m = 12.8 kg, are connected to a very light rigid bar and are attached to an ideal massless spring of spring constant 100 N/m. The system is set into oscillation with an amplitude of 78 cm. At the instant when the acceleration is at its maximum, the 16-kg mass separates from the 12.8-kg mass, which then remains attached to the spring and continues to oscillate. What will be the amplitude of oscillation of the 12.8-kg mass?

A) 78 cm
B) 62 cm
C) 35 cm
D) 98 cm
E) 180 cm