Question: A 0.2 kg mass is attached to a spring k = 10 N/m) and hangs vertically near the earth's surface (g = 9.81 m/s2 ). The mass makes contact with a wall as it moves vertically and a constant frictional force of magnitude 5N acts on the mass as it moves. a) Calculate the amount of work required to pull the spring down by 1 m. b) Calculate the speed of the mass as it passes through the equilibrium position after being pulled down by 1 m. Eq'n U = (1/2)k x^2 Attempt: a) W = U = (1/2)k x^2 (1/2)(10 N/m) (1m)^2 = 5 N*m = 5 J I am lost on part b, someone suggested v = sqrt(k/m) * x ... But I have no clue where they derived this equation... I tried K = 1/2 m v^2 v = sqrt(2K/m) ...But I believe this is incorrect... suggestions?