A vertical spring has one end attached to the ceiling and a 2.50 kg weight attached to the other one. When the system is at rest, the spring is stretched by 20.0 cm. Now let the weight drop from a position in which the spring is not deformed at all. Use the conservation of energy law to find:
a) how fast the weight is moving after it drops 20.0 cm;
b) How far down the weight will drop before starting to come back. What is the weights acceleration when its at the lowest position (give the magnitude and show the direction).