A baby jumper consists of a cloth seat suspended by an elastic cord from the lintel of

Question:

A baby jumper consists of a cloth seat suspended by an elastic cord from the lintel of an open doorway. The unstretched length of the cord is 1.2 m and the cord stretches by 0.20 m when a baby of mass 6.8 kg is placed into the seat. The mother then pulls the seat down by 8.0 cm and releases it?
(a) What is the period of the motion?
(b) What is the maximum speed of the baby?