When a 2.90 kg object is hung vertically on a certain light spring described by hooke's law, the spring stretches 2.36 cm
A) what is the force constant of the spring?
B) if the 2.90-kg object is removed, how far will the spring stretch if a 1.45 kg block is hung on it?
C) how much work must an external agent do to stretch the same spring 8.90 cm from its unstretched position?