Posted by Bruce on .
The motion of a blockspring system is described by x(t) = A sin(ùt). Find ù, if the potential energy equals the kinetic energy at t = 6.11 s.
I'm really not sure how to solve this. It seems that you need more information, either x or A? I appreciate any help, thank you!

Physics 
drwls,
Potential eneregy equals kinetic energy in a simpleharmonicmotion system when the phase angle (measured from the zerodeflection position) is pi/4 radians (or 3 pi/4 or 5 pi/4 or 7 pi/4)
If 6.11*ù = pi/4, then
ù = 0.1285 s^1 is one possibility 
Physics 
Bruce,
Thank you for your help!