Asingle mass m1 = 4.1 kg hangs from a spring in a motionless elevator. the spring is extended x = 13 cm from its unstretched length.

now, three masses m1 = 4.1 kg, m2 = 12.3 kg and m3 = 8.2 kg hang from three identical springs in a motionless elevator. the springs all have the same spring constant that you just calculated above.

now the elevator is moving downward with a velocity of v = -2.8 m/s but accelerating upward with an acceleration of a = 4.2 m/s2. (note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

what is the distance the middle spring is extended from its unstretched length?