10. In the unstretched position the coils of the \( 1.5-\mathrm{kg} \) spring are just touching one another, as shown in part a of the figure. In the stretched position the force P , proportional to x , equals 900 N when \( \mathrm{x}= \) 500 mm . If end A of the spring is suddenly released, determine the velocity \( v_{A} \) of the coil end A , measured positive to the left, as it approaches its unstretched position at \( x=0 \). What happens to the kinetic energy of the spring?
