Show all work : 1. a 30 cm spring is compressed to 2 cm. a force of 200 n was used to do this. how much potential energy is stored in the spring? 2. a 5 kg mass is suspended from a spring. the spring develops 100 j of potential energy. what is the spring constant of the spring? 3. a ball is at rest on top of a 15 meter high hill. it rolls down the hill and is stopped by compressing a spring. if the spring is compressed 56 cm, find the spring constant.4. a 7 kg rock is placed on a spring that has been compressed 48 cm. the spring is released and the rock flies straight upward. as soon as the rock leaves the spring its velocity is 50 m/s. what is the spring constant for the spring? 5. a spring has been stretched 16 cm. the force pulling the spring is reduced so that the stretched length is only 4 cm. by what factor has the potential energy in the spring been reduced? 6. 600n is used to compress a spring to half its initial resting length. how much will the spring be compressed if 800n is used to compress it? 7. 40n stretches a spring from 15 cm to 38 cm. what is the spring constant of the spring?