You have a light spring which obeys Hooke's law. This spring stretches 2.70 cm vertically when a 2.40 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 2.40 kg object with a 1.20 kg object cm (c) the amount of work (in ]) an external agent must do to stretch the spring 8.90 cm from its unstretched position