A custom-designed spring has a restoring force F ( x ) = − ( α x
+ β x 2 ) where x is the stretch from its equilibrium length, α = 2
N/m², and β = 3.3 N/m². A 7-kg gizmo is attached to this spring and stretched 1.5 m over a frictionless, horizontal surface. If the gizmo is released from rest, how fast will it be moving when it passes?
