QUESTION $3$

When $k$ is denoted as the spring constant; s $,$ spring deformation from its unstretched state; v $,$ velocity of the particle or point on the rigid body attached to the spring end, elastic potential energy is defined as

$+(\frac{1}{2})k(v{)}^2$

None of the rest

$-(\frac{1}{2})k(s{)}^2$

$+(\frac{1}{2})k(s{)}^2$