How Would you Approach this Problem? A Physics Oscillating Problem.?

Question

A 0.53 kg object, suspended from an ideal spring of spring constant 23 N/m, is oscillating vertically. How much change of kinetic energy occurs while the object moves from the equilibrium position to a point 4.7 cm lower?

Answer 1

I would use conservation of energy since at the equilibrium position the energy stored in the spring is zero, and, assuming only vertical motion, the energy at that point is:
.5*m*vi^2, where vi is the speed at that moment
let's call this KEi, or starting kinetic energy
now, as the body moves downward it loses potential energy of
m*g*y, and we know that y=.047m
and the spring will store energy of
.5*k*y^2 you know k and y so
m*g*y-.5*k*y^2=
KEf-KEi
since KEf-KEi is the change in kinetic energy, plug in the numbers and calculate
.53*9.8*.047-
.5*23*.043^2

or .223 J

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