A simple harmonic oscillator has spring constant = 8.8N/m , amplitude = 11cm , and maximum speed 4.6m/s .

what is the speed when x=6cm?

total energy= 1/2 K .11^2

now, when .06 cm, then PE = 1/2 k * .06^2 and KE then will be

KE= 1/2 K * .0121-1/2 m v^2

what is m? well, max KE=max Pe
1/2 m 4.6^2=1/2 K *.0121 solve for m

now solve for v in the KE equation.