A block with mass m =6.4 kg is hung from a vertical spring. When the mass hangs in equilibrium, the spring stretches x = 0.27 m. While at this equilibrium position, the mass is then given an initial push downward at v = 5.1 m/s. The block oscillates on the spring without friction.
a) After t = 0.4 s what is the speed of the block?
b) At t = 0.4 s what is the magnitude of the net force on the block?