1. The problem statement, all variables and given/known data 1) A 1.10 kg mass on a spring oscilates horizontally with little friction according to the following equation: x=0.050cos(2.9t), where x is in meters and t in seconds. Find the maximum energy stored in the spring during an oscillation. 2) Find the maximum velocity of the mass. 3) A 55.0 kg circus performer oscillates up and down at the end of a long elastic rope at a rate of once every 9.80 s. The elastic rope obeys Hooke's Law. By how much is the rope extended beyond its unloaded length when the performer hangs at rest? 2. Relevant equations I think for all problems i use an equation dealing with X=Acos(wt) where w is angular freq. 3. The attempt at a solution I've attempted the problem trying to figure out what goes where, but nothing adds up. I know the mass and time for number 1 since it's given, but what to do from there? For problem #2 to get the maximum velocity i should use v=square root(k/m)A, but i dont know what the amplitude is. #3 i dont even know where to get started. If anyone could help a sinking physics student out it would be greatly appreciated.