A body of mass 100 g is attached to a hanging spring whose force constant is 10 N/m. The body is lifted until the spring is in its unstretched state and then released. Calculate the speed of the body when it strikes the table 15 cm below the release point
a. 1 m/s
b. 0.866 m/s
c. 0.225 m/s
d. 1.5 m/s