A block of mass m = 0.4kg is fixed to a spring with spring constant k = 125 N / m and is made to oscillate horizontally on a frictionless surface by displacing the spring an amount d = 0.6 m from its its equilibrium position. With what speed is it moving when it is a distance d/2 from the equilibrium position?
a. 4,6 m/s
b. 9.2 m/s
c. 6.3 m/s
d. 10.1 m/s
