physics..... please....urgent....
posted by jewels .
A 1.0 kg mass is attached to the end of a vertical ideal spring with a force constant of 400 N/m. The mass is set in simple harmonic motion with an amplitude of 10 cm. What is the speed of the 1.0 kg mass at the equilibrium position?

Maximum kinetic energy (which occurs at the equilbrium position) equals maximum stored spring potential energy.
Therefore
(1/2) M Vmax^2 = (1/2) k X^2
Vmax = X*sqrt(k/M)
X is the amplitude, 0.100 m.