You have a light spring which obeys Hooke's law. This spring stretches 2.52 cm vertically when a 2.10 kg object is suspended from it. Determine the following. (a) the force constant of the spring (in N/m) N/m (b) the distance (in cm ) the spring stretches if you replace the 2.10 kg object with a 1.05 kg object cm (c) the amount of work (in J) an external agent must do to stretch the spring 8.70 cm from its unstretched position J