I have two questions: #1.) The velocity of a simple harmonic oscillator is given by v=-7.22(26.0t) (mks units) If the mass is 0.29kg, what is the spring's potential energy at the time t=40.33? MY WORK: First I found k by using ω^2=k/mass. This equaled 196.04. I couldn't really figure out how I was supposed to derive aplitude (A) for that, So i figured since v=-Aω sin (ωt) that A =7.22/2.60. Then i took my (probably not right) amplitude and put it into U=.5kA^2cos^2(ωt). *This didn't work out, possibly because I can't figure out how to get the correct amplitude?? #2.) A 0.28 kg mass is attached to a vertical spring with a spring constant 9.1 N/m and let fall. What is the amplitude of the resulting motion? MY WORK: Since its a vertical spring, i used the equation: y0=mg/k. When I got the y0, i figured this to be twice my aplitude, so i divided it by 2. *Wrong, again because I have issues with amplitude. Please help me!!