A mass that can oscillate without friction on a horizontal surface is attached to a horizontal spring that is pulled to the right 12.5cm and is released from rest. The period of oscillation for the mass is 6.60 s. What is the speed of the mass at t = 1.95 s?
F = kx
x = Acos(2*pi*t/T+[tex]\theta[/tex]0)
The Attempt at a Solution
x = 25*cos(((2[tex]\pi[/tex](1.95))/6.6)+60) = 12.314352
The correct answer according to webwork is 11.4, but i have no idea where I'm going wrong or if i'm doing anything right for that matter. Please help!