Another physics question!?

Question

A spring with spring constant k (N/m) is at its equilibrium length.
a) How much elastic potential energy is stored in the spring?
b) The same spring is stretched so that it is 5.0 cm longer than it was. How much elastic
potential energy is stored in the spring now?
c) A different spring with spring constant three times larger than that in part (a) is
compressed so that it is 4.0 cm shorter than its equilibrium length. How much elastic
potential energy is stored in this spring?

Answer 1

energy in the spring is
.5*k*x^2, where x is elongation or compression from equilibrium
a) is 0 since it is at equilibrium

b)
.5*k*.05^2

c) here the new spring has constant of 3*k
.5*3*k*.04^2

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