Part 2: 1) When increasing the spring constant (k) what do you notice: . . . . ... 2) When decreasing the spring constant (k) what do you notice: 3) Explain why the formula (F=-kx) is negative in some cases? ........ 4) A horizontal spring has a spring constant of 80.0 N/m. What force must be applied to the spring to compress it by 4.0 cm? ... . .... 5) A spring is stretched 0.50 m and the force was 30000 N. What is the spring constant? Part 3: 1) A spring with a constant of 76 N/m is extended by 0.9 m. How much energy is stored in the extended spring? 2) A toy rocket-launcher contains a spring with a spring constant of 35 N/m. How much must the spring be compressed to store 1.5 J of energy? 3) A box is connected to a spring is extended to 200mm, and it stored 3578J of energy. Find the force