1) A 2KG block hangs without vibrating at the end of a spring (k = 500 N/m) that is rising with an upward acceleration of G/3 when the acceleration suddenly ceases (at t=0). (A) What is the angular frequency of oscillation of the block after the acceleration ceases? (B) By what amount is the spring stretched during the time that the elevator car is accelerating? Is part A just asking how long it takes the block to go from its maximum compressed spot to its most stretched spot and back? And I'm having a hard time figuring out B, just where to start. 2) A light balloon filled with helium of density .18 kg/m^3 is tied to a light string of length L = 3meters. The string is tied to the ground forming an inverted pendulum. If the balloon is displaced slightly from equilibrium, it undergoes simple harmonic motion. Determine the period. Take the density of air to be 1.29 KG / M^3. Well the period of a pendulum is... T=2(3.14) multiplied by the square root of mass/(weight/length) Is this the correct equation to use and if so what should go into weight?