A 20-kg mass is attached to a spring with stiffness 200N/m. The damping constant for the system is 140N-sec/m. If the mass is pulled 25cm to the right of the equilibrium and gives an initial leftward velocity of 1m/sec, when will it first return to equilibrium position

Aspring with an unstrained length of 0.071 m and a spring constant of 2.6 n/m hangs vertically downward from the ceiling. a uniform electric field directed vertically upward fills the region containing the spring. a sphere with a mass of 5.29 10-3 kg and a net charge of +7.2 µc is attached to the lower end of the spring. the spring is released slowly, until it reaches equilibrium. the equilibrium length of the spring is 0.058 m. what is the magnitude of the external electric field?