A block with mass m =7.1 kg is hung from a vertical spring. When the mass hangs in equilibrium, the spring stretches x = 0.23 m. While at this equilibrium position, the mass is then given an initial push downward at v = 4.5 m/s. The block oscillates on the spring without friction.
3) After t = 0.37 s what is the speed of the block?
5) At t = 0.37 s what is the magnitude of the net force on the block?
A=sqrt((m*v^2)/k) [from energy conservation, used to find A]
The Attempt at a Solution
Tried modeling number 3 in the equation v=-Asin(ωt+θ), used A=0.689m and ω=6.528 rad/s, yet when I plug in 0.37 s for t, I do not get the right answer. Any help from here? I know I am close. Also, for number 5 i found can find acceleration at that time and then plug into Fnet=ma???