A baby bounces up and down in her crib. Her mass is 13.0 kg, and the crib mattress can be modeled as a light spring with force constant 672 N/m.
(a) The baby soon learns to bounce with maximum amplitude and minimum effort by bending her knees at what frequency?
(b) If she were to use the mattress as a trampoline-losing contact with it for part of each cycle-what minimum amplitude of oscillation does she require?