Part a A toddler of mass 16.8kg is bouncing up and down in her crib. Assume that the crib mattress can be modeled as a light spring with stiffness 792N/m. While the toddler is in contact with the mattress, he behaves like a mass on a spring. What is the natural frequency of his oscillation (in units of Hz)? Part b When can the toddler use the mattress as a trampoline, losing contact with it for part of each bounce? This will happen with the maximum downward acceleration of the mattress becomes greater than the acceleration due to gravity, so that at the top of the bounce the mattress starts moving down faster than the child is falling. Assume that the child has mass 16.8kg and the mattress has stiffness 792N/m. Give the minimum amplitude of bouncing (in m) such that the toddler loses contact with the mattress at the top of the bounce