1. An ornament of mass 23.1 g is attached to a vertical ideal spring with a force constant (spring constant) of 38.4 N/m. The ornament is then lowered very slowly until the spring stops stretching. How much does the spring stretch? 2. If the initial height of the rock in is y1 = h = 4.5-m calculate the rock's velocity when it has fallen to 2.7-m above the ground. 3. Assuming the height of the hill is 31 m, and the roller-coaster car starts from rest at the top, First: Calculate the speed of the roller-coaster car at the bottom of the hill (on your paper) Then answer: At what height will the coaster have 0.36 times its original speed. Take y = 0 at the bottom of the hill. 4. How much power does it take a powerlifter to lift 252-lbs 0.95-m of the ground in 1.8-seconds